21508396 has 48 divisors (see below), whose sum is σ = 47607616. Its totient is φ = 8273664.

The previous prime is 21508379. The next prime is 21508429. The reversal of 21508396 is 69380512.

It is a super-2 number, since 2×21508396² = 925222196985632, which contains 22 as substring.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 12670 + ... + 14266.

Almost surely, 2^21508396 is an apocalyptic number.

21508396 is a gapful number since it is divisible by the number (26) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21508396, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (23803808).

21508396 is an abundant number, since it is smaller than the sum of its proper divisors (26099220).

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

21508396 is a wasteful number, since it uses less digits than its factorization.

21508396 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1658 (or 1656 counting only the distinct ones).

The product of its (nonzero) digits is 12960, while the sum is 34.

The square root of 21508396 is about 4637.7145233401. The cubic root of 21508396 is about 278.1010794729.

It can be divided in two parts, 21508 and 396, that added together give a square (21904 = 148²).

The spelling of 21508396 in words is "twenty-one million, five hundred eight thousand, three hundred ninety-six".