21234177765 has 48 divisors (see below), whose sum is σ = 36999226368. Its totient is φ = 11265585408.

The previous prime is 21234177749. The next prime is 21234177779. The reversal of 21234177765 is 56777143212.

It is not a de Polignac number, because 21234177765 - 2⁴ = 21234177749 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (45).

It is a self number, because there is not a number n which added to its sum of digits gives 21234177765.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 7645057 + ... + 7647833.

It is an arithmetic number, because the mean of its divisors is an integer number (770817216).

Almost surely, 2^21234177765 is an apocalyptic number.

It is an amenable number.

21234177765 is a deficient number, since it is larger than the sum of its proper divisors (15765048603).

21234177765 is a wasteful number, since it uses less digits than its factorization.

21234177765 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3618 (or 3615 counting only the distinct ones).

The product of its digits is 493920, while the sum is 45.

The spelling of 21234177765 in words is "twenty-one billion, two hundred thirty-four million, one hundred seventy-seven thousand, seven hundred sixty-five".