20420501640 has 128 divisors (see below), whose sum is σ = 76378014720. Its totient is φ = 4243219200.

The previous prime is 20420501597. The next prime is 20420501653. The reversal of 20420501640 is 4610502402.

It is a Harshad number since it is a multiple of its sum of digits (24).

It is a self number, because there is not a number n which added to its sum of digits gives 20420501640.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 1095766 + ... + 1114245.

It is an arithmetic number, because the mean of its divisors is an integer number (596703240).

Almost surely, 2^20420501640 is an apocalyptic number.

20420501640 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

20420501640 is an abundant number, since it is smaller than the sum of its proper divisors (55957513080).

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

20420501640 is a wasteful number, since it uses less digits than its factorization.

20420501640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2210043 (or 2210039 counting only the distinct ones).

The product of its (nonzero) digits is 1920, while the sum is 24.

The spelling of 20420501640 in words is "twenty billion, four hundred twenty million, five hundred one thousand, six hundred forty".