20351109857 has 4 divisors (see below), whose sum is σ = 21916579860. Its totient is φ = 18785639856.

The previous prime is 20351109781. The next prime is 20351109859. The reversal of 20351109857 is 75890115302.

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

It can be written as a sum of positive squares in 2 ways, for example, as 7189513681 + 13161596176 = 84791^2 + 114724^2 .

It is a cyclic number.

It is not a de Polignac number, because 20351109857 - 2⁸ = 20351109601 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20351109859) 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, 782734982 + ... + 782735007.

It is an arithmetic number, because the mean of its divisors is an integer number (5479144965).

Almost surely, 2^20351109857 is an apocalyptic number.

It is an amenable number.

20351109857 is a deficient number, since it is larger than the sum of its proper divisors (1565470003).

20351109857 is a wasteful number, since it uses less digits than its factorization.

20351109857 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1565470002.

The product of its (nonzero) digits is 75600, while the sum is 41.

The spelling of 20351109857 in words is "twenty billion, three hundred fifty-one million, one hundred nine thousand, eight hundred fifty-seven".