21209374368 has 672 divisors, whose sum is σ = 78602823936. Its totient is φ = 5482266624.

The previous prime is 21209374327. The next prime is 21209374379. The reversal of 21209374368 is 86347390212.

21209374368 is a `hidden beast` number, since 2 + 1 + 209 + 3 + 7 + 436 + 8 = 666.

It is a tau number, because it is divible by the number of its divisors (672).

It is a super-2 number, since 2×21209374368² (a number of 21 digits) contains 22 as substring.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 111 ways as a sum of consecutive naturals, for example, 205916205 + ... + 205916307.

It is an arithmetic number, because the mean of its divisors is an integer number (116968488).

Almost surely, 2^21209374368 is an apocalyptic number.

21209374368 is a gapful number since it is divisible by the number (28) 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 21209374368, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (39301411968).

21209374368 is an abundant number, since it is smaller than the sum of its proper divisors (57393449568).

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

21209374368 is a wasteful number, since it uses less digits than its factorization.

21209374368 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 248 (or 225 counting only the distinct ones).

The product of its (nonzero) digits is 435456, while the sum is 45.

The spelling of 21209374368 in words is "twenty-one billion, two hundred nine million, three hundred seventy-four thousand, three hundred sixty-eight".