21851701031 has 4 divisors (see below), whose sum is σ = 21852325392. Its totient is φ = 21851076672.

The previous prime is 21851701019. The next prime is 21851701049. The reversal of 21851701031 is 13010715812.

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 21851701031 - 2¹⁰ = 21851700007 is a prime.

It is a super-2 number, since 2×21851701031² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21851700985 and 21851701003.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21851701061) 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, 256355 + ... + 330788.

It is an arithmetic number, because the mean of its divisors is an integer number (5463081348).

Almost surely, 2^21851701031 is an apocalyptic number.

21851701031 is a deficient number, since it is larger than the sum of its proper divisors (624361).

21851701031 is an equidigital number, since it uses as much as digits as its factorization.

21851701031 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 624360.

The product of its (nonzero) digits is 1680, while the sum is 29.

The spelling of 21851701031 in words is "twenty-one billion, eight hundred fifty-one million, seven hundred one thousand, thirty-one".