21122971 has 2 divisors, whose sum is σ = 21122972. Its totient is φ = 21122970.

The previous prime is 21122963. The next prime is 21123013. The reversal of 21122971 is 17922112.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21122971 - 2³ = 21122963 is a prime.

It is equal to p_1337263 and since 21122971 and 1337263 have the same sum of digits, it is a Honaker prime.

It is not a weakly prime, because it can be changed into another prime (21122911) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10561485 + 10561486.

It is an arithmetic number, because the mean of its divisors is an integer number (10561486).

Almost surely, 2^21122971 is an apocalyptic number.

21122971 is a deficient number, since it is larger than the sum of its proper divisors (1).

21122971 is an equidigital number, since it uses as much as digits as its factorization.

21122971 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 504, while the sum is 25.

The square root of 21122971 is about 4595.9733463109. The cubic root of 21122971 is about 276.4298899989.

The spelling of 21122971 in words is "twenty-one million, one hundred twenty-two thousand, nine hundred seventy-one".