21605425263 has 6 divisors (see below), whose sum is σ = 31207836504. Its totient is φ = 14403616836.

The previous prime is 21605425241. The next prime is 21605425319. The reversal of 21605425263 is 36252450612.

21605425263 is a `hidden beast` number, since 2 + 1 + 6 + 0 + 542 + 52 + 63 = 666.

It is not a de Polignac number, because 21605425263 - 2⁸ = 21605425007 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21605425213) 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, 1200301395 + ... + 1200301412.

It is an arithmetic number, because the mean of its divisors is an integer number (5201306084).

Almost surely, 2^21605425263 is an apocalyptic number.

21605425263 is a deficient number, since it is larger than the sum of its proper divisors (9602411241).

21605425263 is a wasteful number, since it uses less digits than its factorization.

21605425263 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2400602813 (or 2400602810 counting only the distinct ones).

The product of its (nonzero) digits is 86400, while the sum is 36.

Adding to 21605425263 its reverse (36252450612), we get a palindrome (57857875875).

The spelling of 21605425263 in words is "twenty-one billion, six hundred five million, four hundred twenty-five thousand, two hundred sixty-three".