21413971 has 2 divisors, whose sum is σ = 21413972. Its totient is φ = 21413970.

The previous prime is 21413947. The next prime is 21413993. The reversal of 21413971 is 17931412.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21413971 - 2⁵ = 21413939 is a prime.

It is not a weakly prime, because it can be changed into another prime (21413941) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10706985 + 10706986.

It is an arithmetic number, because the mean of its divisors is an integer number (10706986).

Almost surely, 2^21413971 is an apocalyptic number.

21413971 is a deficient number, since it is larger than the sum of its proper divisors (1).

21413971 is an equidigital number, since it uses as much as digits as its factorization.

21413971 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1512, while the sum is 28.

The square root of 21413971 is about 4627.5232036155. The cubic root of 21413971 is about 277.6935143466.

The spelling of 21413971 in words is "twenty-one million, four hundred thirteen thousand, nine hundred seventy-one".