56139821 has 2 divisors, whose sum is σ = 56139822. Its totient is φ = 56139820.

The previous prime is 56139799. The next prime is 56139823. The reversal of 56139821 is 12893165.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 55875625 + 264196 = 7475^2 + 514^2 .

It is a cyclic number.

It is not a de Polignac number, because 56139821 - 2¹⁴ = 56123437 is a prime.

Together with 56139823, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (56139823) 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 as a sum of consecutive naturals, namely, 28069910 + 28069911.

It is an arithmetic number, because the mean of its divisors is an integer number (28069911).

Almost surely, 2^56139821 is an apocalyptic number.

It is an amenable number.

56139821 is a deficient number, since it is larger than the sum of its proper divisors (1).

56139821 is an equidigital number, since it uses as much as digits as its factorization.

56139821 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 12960, while the sum is 35.

The square root of 56139821 is about 7492.6511329435. The cubic root of 56139821 is about 382.9043861428.

The spelling of 56139821 in words is "fifty-six million, one hundred thirty-nine thousand, eight hundred twenty-one".