20505428931 has 24 divisors (see below), whose sum is σ = 29659995840. Its totient is φ = 12595486176.

The previous prime is 20505428929. The next prime is 20505428941. The reversal of 20505428931 is 13982450502.

It is not a de Polignac number, because 20505428931 - 2¹ = 20505428929 is a prime.

It is a super-2 number, since 2×20505428931² (a number of 21 digits) contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (39).

It is a self number, because there is not a number n which added to its sum of digits gives 20505428931.

It is not an unprimeable number, because it can be changed into a prime (20505428941) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 240360 + ... + 314298.

It is an arithmetic number, because the mean of its divisors is an integer number (1235833160).

Almost surely, 2^20505428931 is an apocalyptic number.

20505428931 is a deficient number, since it is larger than the sum of its proper divisors (9154566909).

20505428931 is a wasteful number, since it uses less digits than its factorization.

20505428931 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 74515 (or 74502 counting only the distinct ones).

The product of its (nonzero) digits is 86400, while the sum is 39.

The spelling of 20505428931 in words is "twenty billion, five hundred five million, four hundred twenty-eight thousand, nine hundred thirty-one".