21630573 has 12 divisors (see below), whose sum is σ = 31522140. Its totient is φ = 14292096.

The previous prime is 21630563. The next prime is 21630593. The reversal of 21630573 is 37503612.

It is a happy number.

21630573 is a `hidden beast` number, since 21 + 630 + 5 + 7 + 3 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 5008644 + 16621929 = 2238^2 + 4077^2 .

It is not a de Polignac number, because 21630573 - 2⁵ = 21630541 is a prime.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21630563) 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, 9618 + ... + 11651.

It is an arithmetic number, because the mean of its divisors is an integer number (2626845).

Almost surely, 2^21630573 is an apocalyptic number.

It is an amenable number.

21630573 is a deficient number, since it is larger than the sum of its proper divisors (9891567).

21630573 is a wasteful number, since it uses less digits than its factorization.

21630573 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 21388 (or 21385 counting only the distinct ones).

The product of its (nonzero) digits is 3780, while the sum is 27.

The square root of 21630573 is about 4650.8679835059. The cubic root of 21630573 is about 278.6266637162.

The spelling of 21630573 in words is "twenty-one million, six hundred thirty thousand, five hundred seventy-three".