21294621 has 12 divisors (see below), whose sum is σ = 31509660. Its totient is φ = 13849920.

The previous prime is 21294617. The next prime is 21294629. The reversal of 21294621 is 12649212.

It can be written as a sum of positive squares in 2 ways, for example, as 1179396 + 20115225 = 1086^2 + 4485^2 .

It is not a de Polignac number, because 21294621 - 2² = 21294617 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21294629) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 28486 + ... + 29223.

It is an arithmetic number, because the mean of its divisors is an integer number (2625805).

Almost surely, 2^21294621 is an apocalyptic number.

It is an amenable number.

21294621 is a deficient number, since it is larger than the sum of its proper divisors (10215039).

21294621 is a wasteful number, since it uses less digits than its factorization.

21294621 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 57756 (or 57753 counting only the distinct ones).

The product of its digits is 1728, while the sum is 27.

The square root of 21294621 is about 4614.6095176082. The cubic root of 21294621 is about 277.1766479582.

The spelling of 21294621 in words is "twenty-one million, two hundred ninety-four thousand, six hundred twenty-one".