21264240621 has 24 divisors (see below), whose sum is σ = 32316892320. Its totient is φ = 12396960576.

The previous prime is 21264240617. The next prime is 21264240661. The reversal of 21264240621 is 12604246212.

It is not a de Polignac number, because 21264240621 - 2² = 21264240617 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21264240601) 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, 1094086 + ... + 1113351.

It is an arithmetic number, because the mean of its divisors is an integer number (1346537180).

Almost surely, 2^21264240621 is an apocalyptic number.

It is an amenable number.

21264240621 is a deficient number, since it is larger than the sum of its proper divisors (11052651699).

21264240621 is a wasteful number, since it uses less digits than its factorization.

21264240621 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2207485 (or 2207472 counting only the distinct ones).

The product of its (nonzero) digits is 9216, while the sum is 30.

Adding to 21264240621 its reverse (12604246212), we get a palindrome (33868486833).

The spelling of 21264240621 in words is "twenty-one billion, two hundred sixty-four million, two hundred forty thousand, six hundred twenty-one".