21716587 has 2 divisors, whose sum is σ = 21716588. Its totient is φ = 21716586.

The previous prime is 21716573. The next prime is 21716603. The reversal of 21716587 is 78561712.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21716587 - 2¹⁹ = 21192299 is a prime.

It is a super-2 number, since 2×21716587² = 943220301857138, which contains 22 as substring.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (21716507) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10858293 + 10858294.

It is an arithmetic number, because the mean of its divisors is an integer number (10858294).

Almost surely, 2^21716587 is an apocalyptic number.

21716587 is a deficient number, since it is larger than the sum of its proper divisors (1).

21716587 is an equidigital number, since it uses as much as digits as its factorization.

21716587 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 23520, while the sum is 37.

The square root of 21716587 is about 4660.1059000842. The cubic root of 21716587 is about 278.9954950177.

The spelling of 21716587 in words is "twenty-one million, seven hundred sixteen thousand, five hundred eighty-seven".