56561381 has 2 divisors, whose sum is σ = 56561382.
Its totient is φ = 56561380.
The previous prime is 56561371. The next prime is 56561389. The reversal of 56561381 is 18316565.
It is a strong prime.
It can be written as a sum of positive squares in only one way, i.e., 38328481 + 18232900 = 6191^2 + 4270^2
It is a cyclic number.
It is a de Polignac number, because none of the positive numbers 2k-56561381 is a prime.
It is a super-2 number, since 2×565613812 = 6398379641254322, which contains 22 as substring.
It is a congruent number.
It is not a weakly prime, because it can be changed into another prime (56561389) by changing a digit.
It is a polite number, since it can be written as a sum of consecutive naturals, namely, 28280690 + 28280691.
It is an arithmetic number, because the mean of its divisors is an integer number (28280691).
Almost surely, 256561381 is an apocalyptic number.
It is an amenable number.
56561381 is a deficient number, since it is larger than the sum of its proper divisors (1).
56561381 is an equidigital number, since it uses as much as digits as its factorization.
56561381 is an evil number, because the sum of its binary digits is even.
The product of its digits is 21600, while the sum is 35.
The square root of 56561381 is about 7520.7300842405.
The cubic root of 56561381 is about 383.8604206430.
The spelling of 56561381 in words is "fifty-six million, five hundred sixty-one thousand, three hundred eighty-one".