21672571 has 2 divisors, whose sum is σ = 21672572. Its totient is φ = 21672570.

The previous prime is 21672527. The next prime is 21672583. The reversal of 21672571 is 17527612.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21672571 is a prime.

It is not a weakly prime, because it can be changed into another prime (21672271) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10836285 + 10836286.

It is an arithmetic number, because the mean of its divisors is an integer number (10836286).

Almost surely, 2^21672571 is an apocalyptic number.

21672571 is a deficient number, since it is larger than the sum of its proper divisors (1).

21672571 is an equidigital number, since it uses as much as digits as its factorization.

21672571 is an evil number, because the sum of its binary digits is even.

The product of its digits is 5880, while the sum is 31.

The square root of 21672571 is about 4655.3808651924. The cubic root of 21672571 is about 278.8068746517.

The spelling of 21672571 in words is "twenty-one million, six hundred seventy-two thousand, five hundred seventy-one".