56643981 has 8 divisors (see below), whose sum is σ = 76231584. Its totient is φ = 37409520.

The previous prime is 56643973. The next prime is 56644019. The reversal of 56643981 is 18934665.

56643981 = T₉₇₅ + T₉₇₆ + ... + T₁₀₈₁.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 56643981 - 2³ = 56643973 is a prime.

It is a super-2 number, since 2×56643981² = 6417081167056722, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (56643901) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 87910 + ... + 88551.

It is an arithmetic number, because the mean of its divisors is an integer number (9528948).

Almost surely, 2^56643981 is an apocalyptic number.

It is an amenable number.

56643981 is a deficient number, since it is larger than the sum of its proper divisors (19587603).

56643981 is a wasteful number, since it uses less digits than its factorization.

56643981 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 176571.

The product of its digits is 155520, while the sum is 42.

The square root of 56643981 is about 7526.2195689469. The cubic root of 56643981 is about 384.0471879402.

The spelling of 56643981 in words is "fifty-six million, six hundred forty-three thousand, nine hundred eighty-one".