21630615 has 16 divisors (see below), whose sum is σ = 35127168. Its totient is φ = 11363616.

The previous prime is 21630611. The next prime is 21630617. The reversal of 21630615 is 51603612.

It is not a de Polignac number, because 21630615 - 2² = 21630611 is a prime.

It is a plaindrome in base 11.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21630611) 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, 9757 + ... + 11766.

It is an arithmetic number, because the mean of its divisors is an integer number (2195448).

Almost surely, 2^21630615 is an apocalyptic number.

21630615 is a deficient number, since it is larger than the sum of its proper divisors (13496553).

21630615 is a wasteful number, since it uses less digits than its factorization.

21630615 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 21598.

The product of its (nonzero) digits is 1080, while the sum is 24.

The square root of 21630615 is about 4650.8724987899. The cubic root of 21630615 is about 278.6268440522.

The spelling of 21630615 in words is "twenty-one million, six hundred thirty thousand, six hundred fifteen".