20557594639 has 4 divisors (see below), whose sum is σ = 20567325856. Its totient is φ = 20547863424.

The previous prime is 20557594637. The next prime is 20557594667. The reversal of 20557594639 is 93649575502.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 20557594639 - 2¹ = 20557594637 is a prime.

It is a super-2 number, since 2×20557594639² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 20557594639.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20557594637) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 4862439 + ... + 4866664.

It is an arithmetic number, because the mean of its divisors is an integer number (5141831464).

Almost surely, 2^20557594639 is an apocalyptic number.

20557594639 is a deficient number, since it is larger than the sum of its proper divisors (9731217).

20557594639 is an equidigital number, since it uses as much as digits as its factorization.

20557594639 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9731216.

The product of its (nonzero) digits is 10206000, while the sum is 55.

The spelling of 20557594639 in words is "twenty billion, five hundred fifty-seven million, five hundred ninety-four thousand, six hundred thirty-nine".