21730764645 has 64 divisors (see below), whose sum is σ = 41168198400. Its totient is φ = 10979649792.

The previous prime is 21730764637. The next prime is 21730764647. The reversal of 21730764645 is 54646703712.

It is not a de Polignac number, because 21730764645 - 2³ = 21730764637 is a prime.

It is a super-2 number, since 2×21730764645² (a number of 21 digits) contains 22 as substring.

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 21730764645.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21730764647) by changing a digit.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 155469 + ... + 260061.

It is an arithmetic number, because the mean of its divisors is an integer number (643253100).

Almost surely, 2^21730764645 is an apocalyptic number.

It is an amenable number.

21730764645 is a deficient number, since it is larger than the sum of its proper divisors (19437433755).

21730764645 is an equidigital number, since it uses as much as digits as its factorization.

21730764645 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 104638 (or 104620 counting only the distinct ones).

The product of its (nonzero) digits is 846720, while the sum is 45.

The spelling of 21730764645 in words is "twenty-one billion, seven hundred thirty million, seven hundred sixty-four thousand, six hundred forty-five".