21656463 has 4 divisors (see below), whose sum is σ = 28875288. Its totient is φ = 14437640.

The previous prime is 21656461. The next prime is 21656513. The reversal of 21656463 is 36465612.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 21656463 - 2¹ = 21656461 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21656461) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3609408 + ... + 3609413.

It is an arithmetic number, because the mean of its divisors is an integer number (7218822).

Almost surely, 2^21656463 is an apocalyptic number.

21656463 is a deficient number, since it is larger than the sum of its proper divisors (7218825).

21656463 is an equidigital number, since it uses as much as digits as its factorization.

21656463 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7218824.

The product of its digits is 25920, while the sum is 33.

The square root of 21656463 is about 4653.6505025625. The cubic root of 21656463 is about 278.7377837220.

The spelling of 21656463 in words is "twenty-one million, six hundred fifty-six thousand, four hundred sixty-three".