56218991 has 2 divisors, whose sum is σ = 56218992. Its totient is φ = 56218990.

The previous prime is 56218957. The next prime is 56218993. The reversal of 56218991 is 19981265.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 56218991 - 2⁶ = 56218927 is a prime.

Together with 56218993, 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 (56218993) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 28109495 + 28109496.

It is an arithmetic number, because the mean of its divisors is an integer number (28109496).

Almost surely, 2^56218991 is an apocalyptic number.

56218991 is a deficient number, since it is larger than the sum of its proper divisors (1).

56218991 is an equidigital number, since it uses as much as digits as its factorization.

56218991 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 38880, while the sum is 41.

The square root of 56218991 is about 7497.9324483487. The cubic root of 56218991 is about 383.0842958796.

The spelling of 56218991 in words is "fifty-six million, two hundred eighteen thousand, nine hundred ninety-one".