21245138541 has 20 divisors (see below), whose sum is σ = 34621708704. Its totient is φ = 12875841000.

The previous prime is 21245138533. The next prime is 21245138549. The reversal of 21245138541 is 14583154212.

21245138541 is a `hidden beast` number, since 2 + 1 + 24 + 513 + 85 + 41 = 666.

It is an interprime number because it is at equal distance from previous prime (21245138533) and next prime (21245138549).

It is not a de Polignac number, because 21245138541 - 2³ = 21245138533 is a prime.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 21245138496 and 21245138505.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21245138549) by changing a digit.

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 19 ways as a sum of consecutive naturals, for example, 11921185 + ... + 11922966.

Almost surely, 2^21245138541 is an apocalyptic number.

It is an amenable number.

21245138541 is a deficient number, since it is larger than the sum of its proper divisors (13376570163).

21245138541 is a wasteful number, since it uses less digits than its factorization.

21245138541 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 23844174 (or 23844165 counting only the distinct ones).

The product of its digits is 38400, while the sum is 36.

The spelling of 21245138541 in words is "twenty-one billion, two hundred forty-five million, one hundred thirty-eight thousand, five hundred forty-one".