21630737 has 4 divisors (see below), whose sum is σ = 21643776. Its totient is φ = 21617700.

The previous prime is 21630733. The next prime is 21630761. The reversal of 21630737 is 73703612.

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 21630737 - 2² = 21630733 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21630733) 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, 3593 + ... + 7494.

It is an arithmetic number, because the mean of its divisors is an integer number (5410944).

Almost surely, 2^21630737 is an apocalyptic number.

It is an amenable number.

21630737 is a deficient number, since it is larger than the sum of its proper divisors (13039).

21630737 is a wasteful number, since it uses less digits than its factorization.

21630737 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 13038.

The product of its (nonzero) digits is 5292, while the sum is 29.

The square root of 21630737 is about 4650.8856145900. The cubic root of 21630737 is about 278.6273678839.

The spelling of 21630737 in words is "twenty-one million, six hundred thirty thousand, seven hundred thirty-seven".