20640879820 has 48 divisors (see below), whose sum is σ = 47325847968. Its totient is φ = 7499509760.

The previous prime is 20640879799. The next prime is 20640879821. The reversal of 20640879820 is 2897804602.

It is a hoax number, since the sum of its digits (46) coincides with the sum of the digits of its distinct prime factors.

It is not an unprimeable number, because it can be changed into a prime (20640879821) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 229194 + ... + 306286.

It is an arithmetic number, because the mean of its divisors is an integer number (985955166).

Almost surely, 2^20640879820 is an apocalyptic number.

20640879820 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

20640879820 is an abundant number, since it is smaller than the sum of its proper divisors (26684968148).

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

20640879820 is a wasteful number, since it uses less digits than its factorization.

20640879820 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 78330 (or 78328 counting only the distinct ones).

The product of its (nonzero) digits is 387072, while the sum is 46.

The spelling of 20640879820 in words is "twenty billion, six hundred forty million, eight hundred seventy-nine thousand, eight hundred twenty".