56999981 has 4 divisors (see below), whose sum is σ = 60000000. Its totient is φ = 53999964.

The previous prime is 56999947. The next prime is 56999989. The reversal of 56999981 is 18999965.

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 not a de Polignac number, because 56999981 - 2¹⁰ = 56998957 is a prime.

It is a super-2 number, since 2×56999981² = 6497995668000722, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (56999989) 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, 1499981 + ... + 1500018.

It is an arithmetic number, because the mean of its divisors is an integer number (15000000).

Almost surely, 2^56999981 is an apocalyptic number.

It is an amenable number.

56999981 is a deficient number, since it is larger than the sum of its proper divisors (3000019).

56999981 is a wasteful number, since it uses less digits than its factorization.

56999981 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3000018.

The product of its digits is 1574640, while the sum is 56.

The square root of 56999981 is about 7549.8331769649. The cubic root of 56999981 is about 384.8500703666.

The spelling of 56999981 in words is "fifty-six million, nine hundred ninety-nine thousand, nine hundred eighty-one".