21621130 has 8 divisors (see below), whose sum is σ = 38918052. Its totient is φ = 8648448.

The previous prime is 21621121. The next prime is 21621137. The reversal of 21621130 is 3112612.

It can be written as a sum of positive squares in 2 ways, for example, as 21372129 + 249001 = 4623^2 + 499^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is not an unprimeable number, because it can be changed into a prime (21621137) 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, 1081047 + ... + 1081066.

Almost surely, 2^21621130 is an apocalyptic number.

21621130 is a deficient number, since it is larger than the sum of its proper divisors (17296922).

21621130 is a wasteful number, since it uses less digits than its factorization.

21621130 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2162120.

The product of its (nonzero) digits is 72, while the sum is 16.

The square root of 21621130 is about 4649.8526858386. The cubic root of 21621130 is about 278.5861122469.

Adding to 21621130 its reverse (3112612), we get a palindrome (24733742).

The spelling of 21621130 in words is "twenty-one million, six hundred twenty-one thousand, one hundred thirty".