56217781 has 4 divisors (see below), whose sum is σ = 57413952. Its totient is φ = 55021612.

The previous prime is 56217779. The next prime is 56217803. The reversal of 56217781 is 18771265.

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 56217781 - 2¹ = 56217779 is a prime.

It is a super-2 number, since 2×56217781² = 6320877801127922, which contains 22 as substring.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 56217781.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (56217701) 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, 598015 + ... + 598108.

It is an arithmetic number, because the mean of its divisors is an integer number (14353488).

Almost surely, 2^56217781 is an apocalyptic number.

It is an amenable number.

56217781 is a deficient number, since it is larger than the sum of its proper divisors (1196171).

56217781 is a wasteful number, since it uses less digits than its factorization.

56217781 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1196170.

The product of its digits is 23520, while the sum is 37.

The square root of 56217781 is about 7497.8517590040. The cubic root of 56217781 is about 383.0815474885.

The spelling of 56217781 in words is "fifty-six million, two hundred seventeen thousand, seven hundred eighty-one".