21401524521 has 24 divisors (see below), whose sum is σ = 33342361416. Its totient is φ = 13149953280.

The previous prime is 21401524499. The next prime is 21401524609. The reversal of 21401524521 is 12542510412.

It is a happy number.

21401524521 is a `hidden beast` number, since 21 + 40 + 152 + 452 + 1 = 666.

It can be written as a sum of positive squares in 4 ways, for example, as 88736400 + 21312788121 = 9420^2 + 145989^2 .

It is not a de Polignac number, because 21401524521 - 2⁵ = 21401524489 is a prime.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (21401524121) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 63660 + ... + 216461.

It is an arithmetic number, because the mean of its divisors is an integer number (1389265059).

Almost surely, 2^21401524521 is an apocalyptic number.

It is an amenable number.

21401524521 is a deficient number, since it is larger than the sum of its proper divisors (11940836895).

21401524521 is a wasteful number, since it uses less digits than its factorization.

21401524521 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 280793 (or 280790 counting only the distinct ones).

The product of its (nonzero) digits is 3200, while the sum is 27.

The spelling of 21401524521 in words is "twenty-one billion, four hundred one million, five hundred twenty-four thousand, five hundred twenty-one".