20905565837 has 12 divisors (see below), whose sum is σ = 22665937140. Its totient is φ = 19273108608.

The previous prime is 20905565801. The next prime is 20905565851. The reversal of 20905565837 is 73856550902.

It can be written as a sum of positive squares in 6 ways, for example, as 10078955236 + 10826610601 = 100394^2 + 104051^2 .

It is not a de Polignac number, because 20905565837 - 2⁸ = 20905565581 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20905565887) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 57089 + ... + 212297.

It is an arithmetic number, because the mean of its divisors is an integer number (1888828095).

Almost surely, 2^20905565837 is an apocalyptic number.

It is an amenable number.

20905565837 is a deficient number, since it is larger than the sum of its proper divisors (1760371303).

20905565837 is a wasteful number, since it uses less digits than its factorization.

20905565837 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 156032 (or 156019 counting only the distinct ones).

The product of its (nonzero) digits is 2268000, while the sum is 50.

The spelling of 20905565837 in words is "twenty billion, nine hundred five million, five hundred sixty-five thousand, eight hundred thirty-seven".