1531664640 has 720 divisors, whose sum is σ = 6410638080. Its totient is φ = 345047040.

The previous prime is 1531664639. The next prime is 1531664681. The reversal of 1531664640 is 464661351.

It is a happy number.

1531664640 is a `hidden beast` number, since 1 + 5 + 3 + 1 + 6 + 6 + 4 + 640 = 666.

It is a tau number, because it is divible by the number of its divisors (720).

It is a hoax number, since the sum of its digits (36) coincides with the sum of the digits of its distinct prime factors.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a junction number, because it is equal to n+sod(n) for n = 1531664595 and 1531664604.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 79 ways as a sum of consecutive naturals, for example, 19388121 + ... + 19388199.

It is an arithmetic number, because the mean of its divisors is an integer number (8903664).

Almost surely, 2^1531664640 is an apocalyptic number.

1531664640 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 1531664640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (3205319040).

1531664640 is an abundant number, since it is smaller than the sum of its proper divisors (4878973440).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

1531664640 is a wasteful number, since it uses less digits than its factorization.

1531664640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 140 (or 117 counting only the distinct ones).

The product of its (nonzero) digits is 51840, while the sum is 36.

The square root of 1531664640 is about 39136.4873232128. The cubic root of 1531664640 is about 1152.7131001591.

The spelling of 1531664640 in words is "one billion, five hundred thirty-one million, six hundred sixty-four thousand, six hundred forty".