20640874621 has 2 divisors, whose sum is σ = 20640874622. Its totient is φ = 20640874620.

The previous prime is 20640874607. The next prime is 20640874633. The reversal of 20640874621 is 12647804602.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 15397087225 + 5243787396 = 124085^2 + 72414^2 .

It is a cyclic number.

It is not a de Polignac number, because 20640874621 - 2¹⁹ = 20640350333 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20640874021) 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 as a sum of consecutive naturals, namely, 10320437310 + 10320437311.

It is an arithmetic number, because the mean of its divisors is an integer number (10320437311).

Almost surely, 2^20640874621 is an apocalyptic number.

It is an amenable number.

20640874621 is a deficient number, since it is larger than the sum of its proper divisors (1).

20640874621 is an equidigital number, since it uses as much as digits as its factorization.

20640874621 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 129024, while the sum is 40.

The spelling of 20640874621 in words is "twenty billion, six hundred forty million, eight hundred seventy-four thousand, six hundred twenty-one".