987917561 has 4 divisors (see below), whose sum is σ = 1010892432. Its totient is φ = 964942692.

The previous prime is 987917537. The next prime is 987917573. The reversal of 987917561 is 165719789.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-987917561 is a prime.

It is a super-2 number, since 2×987917561² = 1951962214664377442, which contains 22 as substring.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (987913561) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 11487371 + ... + 11487456.

It is an arithmetic number, because the mean of its divisors is an integer number (252723108).

Almost surely, 2^987917561 is an apocalyptic number.

It is an amenable number.

987917561 is a deficient number, since it is larger than the sum of its proper divisors (22974871).

987917561 is a wasteful number, since it uses less digits than its factorization.

987917561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 22974870.

The product of its digits is 952560, while the sum is 53.

The square root of 987917561 is about 31431.1558966577. The cubic root of 987917561 is about 995.9561899758.

The spelling of 987917561 in words is "nine hundred eighty-seven million, nine hundred seventeen thousand, five hundred sixty-one".