21573630 has 48 divisors (see below), whose sum is σ = 60409440. Its totient is φ = 5310144.

The previous prime is 21573583. The next prime is 21573637. The reversal of 21573630 is 3637512.

It is a happy number.

21573630 is a `hidden beast` number, since 21 + 5 + 7 + 3 + 630 = 666.

It is a super-2 number, since 2×21573630² = 930843022753800, which contains 22 as substring.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 21573594 and 21573603.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21573637) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 8050 + ... + 10389.

It is an arithmetic number, because the mean of its divisors is an integer number (1258530).

Almost surely, 2^21573630 is an apocalyptic number.

21573630 is an abundant number, since it is smaller than the sum of its proper divisors (38835810).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21573630 is a wasteful number, since it uses less digits than its factorization.

21573630 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 18465 (or 18462 counting only the distinct ones).

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

The square root of 21573630 is about 4644.7421887549. The cubic root of 21573630 is about 278.3819517382.

The spelling of 21573630 in words is "twenty-one million, five hundred seventy-three thousand, six hundred thirty".