20506457639 has 4 divisors (see below), whose sum is σ = 20507262024. Its totient is φ = 20505653256.

The previous prime is 20506457597. The next prime is 20506457669. The reversal of 20506457639 is 93675460502.

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 20506457639 - 2²⁰ = 20505409063 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 20506457593 and 20506457602.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20506457669) 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, 362657 + ... + 415370.

It is an arithmetic number, because the mean of its divisors is an integer number (5126815506).

Almost surely, 2^20506457639 is an apocalyptic number.

20506457639 is a deficient number, since it is larger than the sum of its proper divisors (804385).

20506457639 is an equidigital number, since it uses as much as digits as its factorization.

20506457639 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 804384.

The product of its (nonzero) digits is 1360800, while the sum is 47.

The spelling of 20506457639 in words is "twenty billion, five hundred six million, four hundred fifty-seven thousand, six hundred thirty-nine".