20857434551 has 2 divisors, whose sum is σ = 20857434552. Its totient is φ = 20857434550.

The previous prime is 20857434529. The next prime is 20857434629. The reversal of 20857434551 is 15543475802.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 20857434551 - 2²⁶ = 20790325687 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20857434511) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10428717275 + 10428717276.

It is an arithmetic number, because the mean of its divisors is an integer number (10428717276).

Almost surely, 2^20857434551 is an apocalyptic number.

20857434551 is a deficient number, since it is larger than the sum of its proper divisors (1).

20857434551 is an equidigital number, since it uses as much as digits as its factorization.

20857434551 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 672000, while the sum is 44.

The spelling of 20857434551 in words is "twenty billion, eight hundred fifty-seven million, four hundred thirty-four thousand, five hundred fifty-one".