21662951 has 4 divisors (see below), whose sum is σ = 21680904. Its totient is φ = 21645000.

The previous prime is 21662939. The next prime is 21662959. The reversal of 21662951 is 15926612.

It is a happy number.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21662951 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21662959) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 7025 + ... + 9626.

It is an arithmetic number, because the mean of its divisors is an integer number (5420226).

Almost surely, 2^21662951 is an apocalyptic number.

21662951 is a deficient number, since it is larger than the sum of its proper divisors (17953).

21662951 is a wasteful number, since it uses less digits than its factorization.

21662951 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 17952.

The product of its digits is 6480, while the sum is 32.

The square root of 21662951 is about 4654.3475375180. The cubic root of 21662951 is about 278.7656163706.

The spelling of 21662951 in words is "twenty-one million, six hundred sixty-two thousand, nine hundred fifty-one".