21990087255591 has 192 divisors, whose sum is σ = 41537700492288. Its totient is φ = 11314813805568.

The previous prime is 21990087255523. The next prime is 21990087255659. The reversal of 21990087255591 is 19555278009912.

21990087255591 is a `hidden beast` number, since 2 + 1 + 9 + 9 + 0 + 0 + 8 + 72 + 5 + 559 + 1 = 666.

It is an interprime number because it is at equal distance from previous prime (21990087255523) and next prime (21990087255659).

It is not a de Polignac number, because 21990087255591 - 2⁹ = 21990087255079 is a prime.

It is a hoax number, since the sum of its digits (63) coincides with the sum of the digits of its distinct prime factors.

It is a Harshad number since it is a multiple of its sum of digits (63).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21990087255791) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (31) of ones.

It is a polite number, since it can be written in 191 ways as a sum of consecutive naturals, for example, 757820115 + ... + 757849131.

It is an arithmetic number, because the mean of its divisors is an integer number (216342190064).

Almost surely, 2^{21990087255591} is an apocalyptic number.

21990087255591 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

21990087255591 is a deficient number, since it is larger than the sum of its proper divisors (19547613236697).

21990087255591 is a wasteful number, since it uses less digits than its factorization.

21990087255591 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 29892 (or 29880 counting only the distinct ones).

The product of its (nonzero) digits is 20412000, while the sum is 63.

The spelling of 21990087255591 in words is "twenty-one trillion, nine hundred ninety billion, eighty-seven million, two hundred fifty-five thousand, five hundred ninety-one".