21555959040 has 864 divisors, whose sum is σ = 97955020800. Its totient is φ = 4240097280.

The previous prime is 21555959017. The next prime is 21555959129. The reversal of 21555959040 is 4095955512.

21555959040 is a `hidden beast` number, since 2 + 1 + 5 + 5 + 59 + 590 + 4 + 0 = 666.

It is a Harshad number since it is a multiple of its sum of digits (45).

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 16853121 + ... + 16854399.

Almost surely, 2^21555959040 is an apocalyptic number.

21555959040 is a gapful number since it is divisible by the number (20) 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 21555959040, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (48977510400).

21555959040 is an abundant number, since it is smaller than the sum of its proper divisors (76399061760).

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

21555959040 is a wasteful number, since it uses less digits than its factorization.

21555959040 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1343 (or 1326 counting only the distinct ones).

The product of its (nonzero) digits is 405000, while the sum is 45.

The spelling of 21555959040 in words is "twenty-one billion, five hundred fifty-five million, nine hundred fifty-nine thousand, forty".