987972561 has 12 divisors (see below), whose sum is σ = 1511017092. Its totient is φ = 619904256.

The previous prime is 987972541. The next prime is 987972617. The reversal of 987972561 is 165279789.

987972561 is a `hidden beast` number, since 9 + 8 + 7 + 9 + 72 + 561 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 909384336 + 78588225 = 30156^2 + 8865^2 .

It is not a de Polignac number, because 987972561 - 2⁵ = 987972529 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 987972498 and 987972507.

It is not an unprimeable number, because it can be changed into a prime (987972541) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 3228516 + ... + 3228821.

It is an arithmetic number, because the mean of its divisors is an integer number (125918091).

Almost surely, 2^987972561 is an apocalyptic number.

It is an amenable number.

987972561 is a deficient number, since it is larger than the sum of its proper divisors (523044531).

987972561 is a wasteful number, since it uses less digits than its factorization.

987972561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6457360 (or 6457357 counting only the distinct ones).

The product of its digits is 1905120, while the sum is 54.

The square root of 987972561 is about 31432.0308125326. The cubic root of 987972561 is about 995.9746721435.

The spelling of 987972561 in words is "nine hundred eighty-seven million, nine hundred seventy-two thousand, five hundred sixty-one".