21457394868 has 384 divisors, whose sum is σ = 68022599680. Its totient is φ = 5106032640.

The previous prime is 21457394851. The next prime is 21457394873. The reversal of 21457394868 is 86849375412.

It is a happy number.

It is a Harshad number since it is a multiple of its sum of digits (57).

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 127 ways as a sum of consecutive naturals, for example, 46952496 + ... + 46952952.

Almost surely, 2^21457394868 is an apocalyptic number.

21457394868 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 21457394868, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (34011299840).

21457394868 is an abundant number, since it is smaller than the sum of its proper divisors (46565204812).

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

21457394868 is a wasteful number, since it uses less digits than its factorization.

21457394868 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 607 (or 605 counting only the distinct ones).

The product of its digits is 11612160, while the sum is 57.

The spelling of 21457394868 in words is "twenty-one billion, four hundred fifty-seven million, three hundred ninety-four thousand, eight hundred sixty-eight".