61887985731 has 144 divisors (see below), whose sum is σ = 109154990880. Its totient is φ = 33469562880.

The previous prime is 61887985711. The next prime is 61887985781. The reversal of 61887985731 is 13758978816.

61887985731 is a `hidden beast` number, since 618 + 8 + 7 + 9 + 8 + 5 + 7 + 3 + 1 = 666.

It is not a de Polignac number, because 61887985731 - 2⁷ = 61887985603 is a prime.

It is a super-2 number, since 2×61887985731² (a number of 22 digits) contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (61887985711) by changing a digit.

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 143 ways as a sum of consecutive naturals, for example, 159094885 + ... + 159095273.

It is an arithmetic number, because the mean of its divisors is an integer number (758020770).

Almost surely, 2^61887985731 is an apocalyptic number.

61887985731 is a deficient number, since it is larger than the sum of its proper divisors (47267005149).

61887985731 is a wasteful number, since it uses less digits than its factorization.

61887985731 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 726 (or 710 counting only the distinct ones).

The product of its digits is 20321280, while the sum is 63.

The spelling of 61887985731 in words is "sixty-one billion, eight hundred eighty-seven million, nine hundred eighty-five thousand, seven hundred thirty-one".