21603867765 has 16 divisors (see below), whose sum is σ = 34838366208. Its totient is φ = 11431336896.

The previous prime is 21603867763. The next prime is 21603867773. The reversal of 21603867765 is 56776830612.

It is not a de Polignac number, because 21603867765 - 2¹ = 21603867763 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21603867763) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 5668402 + ... + 5672211.

It is an arithmetic number, because the mean of its divisors is an integer number (2177397888).

Almost surely, 2^21603867765 is an apocalyptic number.

It is an amenable number.

21603867765 is a deficient number, since it is larger than the sum of its proper divisors (13234498443).

21603867765 is a wasteful number, since it uses less digits than its factorization.

21603867765 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 11340748.

The product of its (nonzero) digits is 2540160, while the sum is 51.

The spelling of 21603867765 in words is "twenty-one billion, six hundred three million, eight hundred sixty-seven thousand, seven hundred sixty-five".