21965951 has 4 divisors (see below), whose sum is σ = 25103952. Its totient is φ = 18827952.

The previous prime is 21965927. The next prime is 21965959. The reversal of 21965951 is 15956912.

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-21965951 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 (21965959) 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, 1568990 + ... + 1569003.

It is an arithmetic number, because the mean of its divisors is an integer number (6275988).

Almost surely, 2^21965951 is an apocalyptic number.

21965951 is a deficient number, since it is larger than the sum of its proper divisors (3138001).

21965951 is an equidigital number, since it uses as much as digits as its factorization.

21965951 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3138000.

The product of its digits is 24300, while the sum is 38.

The square root of 21965951 is about 4686.7847187598. The cubic root of 21965951 is about 280.0593029152.

The spelling of 21965951 in words is "twenty-one million, nine hundred sixty-five thousand, nine hundred fifty-one".