21945951 has 16 divisors (see below), whose sum is σ = 32815200. Its totient is φ = 14494464.

The previous prime is 21945943. The next prime is 21945961. The reversal of 21945951 is 15954912.

It is not a de Polignac number, because 21945951 - 2³ = 21945943 is a prime.

It is a hoax number, since the sum of its digits (36) coincides with the sum of the digits of its distinct prime factors.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21945961) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 786 + ... + 6671.

It is an arithmetic number, because the mean of its divisors is an integer number (2050950).

Almost surely, 2^21945951 is an apocalyptic number.

21945951 is a deficient number, since it is larger than the sum of its proper divisors (10869249).

21945951 is a wasteful number, since it uses less digits than its factorization.

21945951 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7575 (or 7569 counting only the distinct ones).

The product of its digits is 16200, while the sum is 36.

The square root of 21945951 is about 4684.6505739489. The cubic root of 21945951 is about 279.9742790999.

The spelling of 21945951 in words is "twenty-one million, nine hundred forty-five thousand, nine hundred fifty-one".