20645818765 has 32 divisors (see below), whose sum is σ = 30109968000. Its totient is φ = 13382181120.

The previous prime is 20645818723. The next prime is 20645818799. The reversal of 20645818765 is 56781854602.

It is a happy number.

It is not a de Polignac number, because 20645818765 - 2¹¹ = 20645816717 is a prime.

It is a super-2 number, since 2×20645818765² (a number of 21 digits) contains 22 as substring.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 477115 + ... + 518584.

It is an arithmetic number, because the mean of its divisors is an integer number (940936500).

Almost surely, 2^20645818765 is an apocalyptic number.

It is an amenable number.

20645818765 is a deficient number, since it is larger than the sum of its proper divisors (9464149235).

20645818765 is a wasteful number, since it uses less digits than its factorization.

20645818765 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 995757.

The product of its (nonzero) digits is 3225600, while the sum is 52.

The spelling of 20645818765 in words is "twenty billion, six hundred forty-five million, eight hundred eighteen thousand, seven hundred sixty-five".