21242971 has 2 divisors, whose sum is σ = 21242972. Its totient is φ = 21242970.

The previous prime is 21242959. The next prime is 21242981. The reversal of 21242971 is 17924212.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21242971 - 2⁵ = 21242939 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (21242941) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10621485 + 10621486.

It is an arithmetic number, because the mean of its divisors is an integer number (10621486).

Almost surely, 2^21242971 is an apocalyptic number.

21242971 is a deficient number, since it is larger than the sum of its proper divisors (1).

21242971 is an equidigital number, since it uses as much as digits as its factorization.

21242971 is an evil number, because the sum of its binary digits is even.

The product of its digits is 2016, while the sum is 28.

The square root of 21242971 is about 4609.0097634958. The cubic root of 21242971 is about 276.9523696597.

The spelling of 21242971 in words is "twenty-one million, two hundred forty-two thousand, nine hundred seventy-one".