21056051 has 2 divisors, whose sum is σ = 21056052. Its totient is φ = 21056050.

The previous prime is 21056039. The next prime is 21056053. The reversal of 21056051 is 15065012.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21056051 is a prime.

Together with 21056053, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (21056053) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10528025 + 10528026.

It is an arithmetic number, because the mean of its divisors is an integer number (10528026).

Almost surely, 2^21056051 is an apocalyptic number.

21056051 is a deficient number, since it is larger than the sum of its proper divisors (1).

21056051 is an equidigital number, since it uses as much as digits as its factorization.

21056051 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 300, while the sum is 20.

The square root of 21056051 is about 4588.6872850522. The cubic root of 21056051 is about 276.1376606211.

The spelling of 21056051 in words is "twenty-one million, fifty-six thousand, fifty-one".