21256967 has 4 divisors (see below), whose sum is σ = 21296376. Its totient is φ = 21217560.

The previous prime is 21256931. The next prime is 21256997. The reversal of 21256967 is 76965212.

It is a happy number.

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 21256967 - 2¹² = 21252871 is a prime.

It is an alternating number because its digits alternate between even and odd.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21256967.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21256997) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 18884 + ... + 19977.

It is an arithmetic number, because the mean of its divisors is an integer number (5324094).

Almost surely, 2^21256967 is an apocalyptic number.

21256967 is a deficient number, since it is larger than the sum of its proper divisors (39409).

21256967 is an equidigital number, since it uses as much as digits as its factorization.

21256967 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 39408.

The product of its digits is 45360, while the sum is 38.

The square root of 21256967 is about 4610.5278439675. The cubic root of 21256967 is about 277.0131799608.

The spelling of 21256967 in words is "twenty-one million, two hundred fifty-six thousand, nine hundred sixty-seven".