20640462021 has 12 divisors (see below), whose sum is σ = 30048758272. Its totient is φ = 13651958376.

The previous prime is 20640461977. The next prime is 20640462103. The reversal of 20640462021 is 12026404602.

It is not a de Polignac number, because 20640462021 - 2¹⁵ = 20640429253 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20640462421) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 9027931 + ... + 9030216.

Almost surely, 2^20640462021 is an apocalyptic number.

It is an amenable number.

20640462021 is a deficient number, since it is larger than the sum of its proper divisors (9408296251).

20640462021 is a wasteful number, since it uses less digits than its factorization.

20640462021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 18058280 (or 18058277 counting only the distinct ones).

The product of its (nonzero) digits is 4608, while the sum is 27.

Adding to 20640462021 its reverse (12026404602), we get a palindrome (32666866623).

The spelling of 20640462021 in words is "twenty billion, six hundred forty million, four hundred sixty-two thousand, twenty-one".