21630396 has 48 divisors (see below), whose sum is σ = 53222400. Its totient is φ = 6823872.

The previous prime is 21630391. The next prime is 21630421. The reversal of 21630396 is 69303612.

It is a happy number.

It is a super-2 number, since 2×21630396² = 935748062233632, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21630391) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 29725 + ... + 30443.

It is an arithmetic number, because the mean of its divisors is an integer number (1108800).

Almost surely, 2^21630396 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21630396, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (26611200).

21630396 is an abundant number, since it is smaller than the sum of its proper divisors (31592004).

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

21630396 is a wasteful number, since it uses less digits than its factorization.

21630396 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 858 (or 856 counting only the distinct ones).

The product of its (nonzero) digits is 5832, while the sum is 30.

The square root of 21630396 is about 4650.8489547608. The cubic root of 21630396 is about 278.6259037262.

The spelling of 21630396 in words is "twenty-one million, six hundred thirty thousand, three hundred ninety-six".