20857434587 has 4 divisors (see below), whose sum is σ = 22753565016. Its totient is φ = 18961304160.

The previous prime is 20857434551. The next prime is 20857434629. The reversal of 20857434587 is 78543475802.

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 20857434587 - 2²⁴ = 20840657371 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20857424587) 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, 948065198 + ... + 948065219.

It is an arithmetic number, because the mean of its divisors is an integer number (5688391254).

Almost surely, 2^20857434587 is an apocalyptic number.

20857434587 is a deficient number, since it is larger than the sum of its proper divisors (1896130429).

20857434587 is a wasteful number, since it uses less digits than its factorization.

20857434587 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1896130428.

The product of its (nonzero) digits is 7526400, while the sum is 53.

The spelling of 20857434587 in words is "twenty billion, eight hundred fifty-seven million, four hundred thirty-four thousand, five hundred eighty-seven".