21987521575 has 12 divisors (see below), whose sum is σ = 27271626280. Its totient is φ = 17585436960.

The previous prime is 21987521561. The next prime is 21987521593. The reversal of 21987521575 is 57512578912.

It is a de Polignac number, because none of the positive numbers 2^k-21987521575 is a prime.

It is a super-2 number, since 2×21987521575² (a number of 21 digits) contains 22 as substring.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 14880 + ... + 210229.

Almost surely, 2^21987521575 is an apocalyptic number.

21987521575 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

21987521575 is a deficient number, since it is larger than the sum of its proper divisors (5284104705).

21987521575 is a wasteful number, since it uses less digits than its factorization.

21987521575 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 229026 (or 229021 counting only the distinct ones).

The product of its digits is 1764000, while the sum is 52.

The spelling of 21987521575 in words is "twenty-one billion, nine hundred eighty-seven million, five hundred twenty-one thousand, five hundred seventy-five".