21630051 has 32 divisors (see below), whose sum is σ = 34045440. Its totient is φ = 13543200.

The previous prime is 21630031. The next prime is 21630061. The reversal of 21630051 is 15003612.

It is not a de Polignac number, because 21630051 - 2⁵ = 21630019 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21630031) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 37596 + ... + 38166.

It is an arithmetic number, because the mean of its divisors is an integer number (1063920).

Almost surely, 2^21630051 is an apocalyptic number.

21630051 is a deficient number, since it is larger than the sum of its proper divisors (12415389).

21630051 is a wasteful number, since it uses less digits than its factorization.

21630051 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 664 (or 658 counting only the distinct ones).

The product of its (nonzero) digits is 180, while the sum is 18.

The square root of 21630051 is about 4650.8118646103. The cubic root of 21630051 is about 278.6244223780.

Adding to 21630051 its reverse (15003612), we get a palindrome (36633663).

The spelling of 21630051 in words is "twenty-one million, six hundred thirty thousand, fifty-one".