21630413 has 12 divisors (see below), whose sum is σ = 25639740. Its totient is φ = 18188352.

The previous prime is 21630391. The next prime is 21630421. The reversal of 21630413 is 31403612.

It can be written as a sum of positive squares in 2 ways, for example, as 8684809 + 12945604 = 2947^2 + 3598^2 .

It is not a de Polignac number, because 21630413 - 2¹⁴ = 21614029 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21630013) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 1568 + ... + 6761.

It is an arithmetic number, because the mean of its divisors is an integer number (2136645).

Almost surely, 2^21630413 is an apocalyptic number.

It is an amenable number.

21630413 is a deficient number, since it is larger than the sum of its proper divisors (4009327).

21630413 is an equidigital number, since it uses as much as digits as its factorization.

21630413 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8396 (or 8389 counting only the distinct ones).

The product of its (nonzero) digits is 432, while the sum is 20.

The square root of 21630413 is about 4650.8507823838. The cubic root of 21630413 is about 278.6259767198.

The spelling of 21630413 in words is "twenty-one million, six hundred thirty thousand, four hundred thirteen".