21456961 has 4 divisors (see below), whose sum is σ = 21482800. Its totient is φ = 21431124.

The previous prime is 21456959. The next prime is 21456971. The reversal of 21456961 is 16965412.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 21456961 - 2¹ = 21456959 is a prime.

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

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21456901) 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, 11631 + ... + 13348.

It is an arithmetic number, because the mean of its divisors is an integer number (5370700).

Almost surely, 2^21456961 is an apocalyptic number.

It is an amenable number.

21456961 is a deficient number, since it is larger than the sum of its proper divisors (25839).

21456961 is an equidigital number, since it uses as much as digits as its factorization.

21456961 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 25838.

The product of its digits is 12960, while the sum is 34.

The square root of 21456961 is about 4632.1659080823. The cubic root of 21456961 is about 277.8792196550.

It can be divided in two parts, 214 and 56961, that added together give a palindrome (57175).

The spelling of 21456961 in words is "twenty-one million, four hundred fifty-six thousand, nine hundred sixty-one".