21251967 has 16 divisors (see below), whose sum is σ = 31059072. Its totient is φ = 12818720.

The previous prime is 21251941. The next prime is 21251987. The reversal of 21251967 is 76915212.

It is a cyclic number.

It is not a de Polignac number, because 21251967 - 2⁶ = 21251903 is a prime.

It is a super-2 number, since 2×21251967² = 903292202738178, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (33).

It is a plaindrome in base 16.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21251987) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 6073 + ... + 8909.

It is an arithmetic number, because the mean of its divisors is an integer number (1941192).

Almost surely, 2^21251967 is an apocalyptic number.

21251967 is a deficient number, since it is larger than the sum of its proper divisors (9807105).

21251967 is a wasteful number, since it uses less digits than its factorization.

21251967 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3078.

The product of its digits is 7560, while the sum is 33.

The square root of 21251967 is about 4609.9855748147. The cubic root of 21251967 is about 276.9914588547.

The spelling of 21251967 in words is "twenty-one million, two hundred fifty-one thousand, nine hundred sixty-seven".