15661578240 has 576 divisors, whose sum is σ = 67704698880. Its totient is φ = 3252879360.

The previous prime is 15661578227. The next prime is 15661578271. The reversal of 15661578240 is 4287516651.

15661578240 is a `hidden beast` number, since 1 + 5 + 6 + 615 + 7 + 8 + 24 + 0 = 666.

It is a tau number, because it is divible by the number of its divisors (576).

It is a Harshad number since it is a multiple of its sum of digits (45).

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 7095217 + ... + 7097423.

It is an arithmetic number, because the mean of its divisors is an integer number (117542880).

Almost surely, 2^15661578240 is an apocalyptic number.

15661578240 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 15661578240, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (33852349440).

15661578240 is an abundant number, since it is smaller than the sum of its proper divisors (52043120640).

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

15661578240 is a wasteful number, since it uses less digits than its factorization.

15661578240 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2258 (or 2235 counting only the distinct ones).

The product of its (nonzero) digits is 403200, while the sum is 45.

The spelling of 15661578240 in words is "fifteen billion, six hundred sixty-one million, five hundred seventy-eight thousand, two hundred forty".