21489250581 has 12 divisors (see below), whose sum is σ = 31041366720. Its totient is φ = 14325549480.

The previous prime is 21489250529. The next prime is 21489250619. The reversal of 21489250581 is 18505298412.

21489250581 is a `hidden beast` number, since 2 + 1 + 48 + 9 + 25 + 0 + 581 = 666.

It is not a de Polignac number, because 21489250581 - 2¹⁹ = 21488726293 is a prime.

It is a super-2 number, since 2×21489250581² (a number of 21 digits) contains 22 as substring.

It is a hoax number, since the sum of its digits (45) coincides with the sum of the digits of its distinct prime factors.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21489250511) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 283990 + ... + 351608.

It is an arithmetic number, because the mean of its divisors is an integer number (2586780560).

Almost surely, 2^21489250581 is an apocalyptic number.

It is an amenable number.

21489250581 is a deficient number, since it is larger than the sum of its proper divisors (9552116139).

21489250581 is a wasteful number, since it uses less digits than its factorization.

21489250581 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 102936 (or 102933 counting only the distinct ones).

The product of its (nonzero) digits is 230400, while the sum is 45.

The spelling of 21489250581 in words is "twenty-one billion, four hundred eighty-nine million, two hundred fifty thousand, five hundred eighty-one".