661538994480 has 600 divisors, whose sum is σ = 2843414161632. Its totient is φ = 139575840768.

The previous prime is 661538994469. The next prime is 661538994503. The reversal of 661538994480 is 84499835166.

661538994480 is a `hidden beast` number, since 6 + 6 + 1 + 538 + 9 + 94 + 4 + 8 + 0 = 666.

It is a Harshad number since it is a multiple of its sum of digits (63).

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 119 ways as a sum of consecutive naturals, for example, 7622692 + ... + 7708988.

Almost surely, 2^661538994480 is an apocalyptic number.

661538994480 is a gapful number since it is divisible by the number (60) 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 661538994480, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1421707080816).

661538994480 is an abundant number, since it is smaller than the sum of its proper divisors (2181875167152).

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

661538994480 is a wasteful number, since it uses less digits than its factorization.

661538994480 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 86355 (or 86327 counting only the distinct ones).

The product of its (nonzero) digits is 44789760, while the sum is 63.

The spelling of 661538994480 in words is "six hundred sixty-one billion, five hundred thirty-eight million, nine hundred ninety-four thousand, four hundred eighty".