21712259 has 2 divisors, whose sum is σ = 21712260. Its totient is φ = 21712258.

The previous prime is 21712241. The next prime is 21712267. The reversal of 21712259 is 95221712.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21712259 - 2²⁴ = 4935043 is a prime.

It is not a weakly prime, because it can be changed into another prime (21712289) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10856129 + 10856130.

It is an arithmetic number, because the mean of its divisors is an integer number (10856130).

Almost surely, 2^21712259 is an apocalyptic number.

21712259 is a deficient number, since it is larger than the sum of its proper divisors (1).

21712259 is an equidigital number, since it uses as much as digits as its factorization.

21712259 is an evil number, because the sum of its binary digits is even.

The product of its digits is 2520, while the sum is 29.

The square root of 21712259 is about 4659.6415098160. The cubic root of 21712259 is about 278.9769596814.

The spelling of 21712259 in words is "twenty-one million, seven hundred twelve thousand, two hundred fifty-nine".