21717963 has 10 divisors (see below), whose sum is σ = 32443004. Its totient is φ = 14478588.

The previous prime is 21717961. The next prime is 21717973. The reversal of 21717963 is 36971712.

It is a happy number.

It is not a de Polignac number, because 21717963 - 2¹ = 21717961 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21717961) by changing a digit.

It is a polite number, since it can be written in 9 ways as a sum of consecutive naturals, for example, 133981 + ... + 134142.

Almost surely, 2^21717963 is an apocalyptic number.

21717963 is a deficient number, since it is larger than the sum of its proper divisors (10725041).

21717963 is an equidigital number, since it uses as much as digits as its factorization.

21717963 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 268135 (or 268126 counting only the distinct ones).

The product of its digits is 15876, while the sum is 36.

The square root of 21717963 is about 4660.2535338756. The cubic root of 21717963 is about 279.0013874367.

The spelling of 21717963 in words is "twenty-one million, seven hundred seventeen thousand, nine hundred sixty-three".