21555249408 has 216 divisors, whose sum is σ = 77485227456. Its totient is φ = 5598720000.

The previous prime is 21555249389. The next prime is 21555249421. The reversal of 21555249408 is 80494255512.

21555249408 is a `hidden beast` number, since 2 + 1 + 5 + 552 + 4 + 94 + 0 + 8 = 666.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 116658 + ... + 238158.

Almost surely, 2^21555249408 is an apocalyptic number.

21555249408 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 21555249408, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (38742613728).

21555249408 is an abundant number, since it is smaller than the sum of its proper divisors (55929978048).

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

21555249408 is a wasteful number, since it uses less digits than its factorization.

21555249408 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 121541 (or 121524 counting only the distinct ones).

The product of its (nonzero) digits is 576000, while the sum is 45.

The spelling of 21555249408 in words is "twenty-one billion, five hundred fifty-five million, two hundred forty-nine thousand, four hundred eight".