21582693981 has 6 divisors (see below), whose sum is σ = 31175002430. Its totient is φ = 14388462648.

The previous prime is 21582693971. The next prime is 21582693989. The reversal of 21582693981 is 18939628512.

21582693981 is a `hidden beast` number, since 21 + 582 + 6 + 9 + 39 + 8 + 1 = 666.

It can be written as a sum of positive squares in only one way, i.e., 20803446756 + 779247225 = 144234^2 + 27915^2 .

It is not a de Polignac number, because 21582693981 - 2⁵ = 21582693949 is a prime.

It is a super-2 number, since 2×21582693981² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21582693989) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 1199038546 + ... + 1199038563.

Almost surely, 2^21582693981 is an apocalyptic number.

It is an amenable number.

21582693981 is a deficient number, since it is larger than the sum of its proper divisors (9592308449).

21582693981 is a wasteful number, since it uses less digits than its factorization.

21582693981 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2398077115 (or 2398077112 counting only the distinct ones).

The product of its digits is 1866240, while the sum is 54.

The spelling of 21582693981 in words is "twenty-one billion, five hundred eighty-two million, six hundred ninety-three thousand, nine hundred eighty-one".