56981987 has 4 divisors (see below), whose sum is σ = 57417096. Its totient is φ = 56546880.

The previous prime is 56981957. The next prime is 56981993. The reversal of 56981987 is 78918965.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 56981987 - 2¹⁸ = 56719843 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (56981917) 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, 217358 + ... + 217619.

It is an arithmetic number, because the mean of its divisors is an integer number (14354274).

Almost surely, 2^56981987 is an apocalyptic number.

56981987 is a deficient number, since it is larger than the sum of its proper divisors (435109).

56981987 is a wasteful number, since it uses less digits than its factorization.

56981987 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 435108.

The product of its digits is 1088640, while the sum is 53.

The square root of 56981987 is about 7548.6414009410. The cubic root of 56981987 is about 384.8095690607.

The spelling of 56981987 in words is "fifty-six million, nine hundred eighty-one thousand, nine hundred eighty-seven".