20640200721 has 32 divisors (see below), whose sum is σ = 31731529728. Its totient is φ = 11689833600.

The previous prime is 20640200719. The next prime is 20640200773. The reversal of 20640200721 is 12700204602.

It is not a de Polignac number, because 20640200721 - 2¹ = 20640200719 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 20640200691 and 20640200700.

It is not an unprimeable number, because it can be changed into a prime (20640205721) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 1442026 + ... + 1456268.

It is an arithmetic number, because the mean of its divisors is an integer number (991610304).

Almost surely, 2^20640200721 is an apocalyptic number.

20640200721 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

It is an amenable number.

20640200721 is a deficient number, since it is larger than the sum of its proper divisors (11091329007).

20640200721 is a wasteful number, since it uses less digits than its factorization.

20640200721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 14861.

The product of its (nonzero) digits is 1344, while the sum is 24.

The spelling of 20640200721 in words is "twenty billion, six hundred forty million, two hundred thousand, seven hundred twenty-one".