21657138048 has 256 divisors, whose sum is σ = 78670233600. Its totient is φ = 5711689728.

The previous prime is 21657138017. The next prime is 21657138059. The reversal of 21657138048 is 84083175612.

21657138048 is a `hidden beast` number, since 2 + 1 + 6 + 571 + 38 + 0 + 48 = 666.

It is a junction number, because it is equal to n+sod(n) for n = 21657137994 and 21657138012.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 280065 + ... + 348927.

It is an arithmetic number, because the mean of its divisors is an integer number (307305600).

Almost surely, 2^21657138048 is an apocalyptic number.

21657138048 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 21657138048, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (39335116800).

21657138048 is an abundant number, since it is smaller than the sum of its proper divisors (57013095552).

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

21657138048 is a wasteful number, since it uses less digits than its factorization.

21657138048 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 68906 (or 68888 counting only the distinct ones).

The product of its (nonzero) digits is 322560, while the sum is 45.

The spelling of 21657138048 in words is "twenty-one billion, six hundred fifty-seven million, one hundred thirty-eight thousand, forty-eight".