20565421836 has 24 divisors (see below), whose sum is σ = 48291631920. Its totient is φ = 6811476672.

The previous prime is 20565421823. The next prime is 20565421853. The reversal of 20565421836 is 63812456502.

It is a super-2 number, since 2×20565421836² (a number of 21 digits) contains 22 as substring.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 5456031 + ... + 5459798.

It is an arithmetic number, because the mean of its divisors is an integer number (2012151330).

Almost surely, 2^20565421836 is an apocalyptic number.

It is an amenable number.

20565421836 is an abundant number, since it is smaller than the sum of its proper divisors (27726210084).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

20565421836 is a wasteful number, since it uses less digits than its factorization.

20565421836 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10915993 (or 10915991 counting only the distinct ones).

The product of its (nonzero) digits is 345600, while the sum is 42.

The spelling of 20565421836 in words is "twenty billion, five hundred sixty-five million, four hundred twenty-one thousand, eight hundred thirty-six".