20909515823 has 32 divisors (see below), whose sum is σ = 26196048000. Its totient is φ = 16273281024.

The previous prime is 20909515777. The next prime is 20909515853. The reversal of 20909515823 is 32851590902.

It is not a de Polignac number, because 20909515823 - 2³⁴ = 3729646639 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20909515853) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 8201753 + ... + 8204301.

It is an arithmetic number, because the mean of its divisors is an integer number (818626500).

Almost surely, 2^20909515823 is an apocalyptic number.

20909515823 is a deficient number, since it is larger than the sum of its proper divisors (5286532177).

20909515823 is a wasteful number, since it uses less digits than its factorization.

20909515823 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4979.

The product of its (nonzero) digits is 194400, while the sum is 44.

The spelling of 20909515823 in words is "twenty billion, nine hundred nine million, five hundred fifteen thousand, eight hundred twenty-three".