21851253943 has 16 divisors (see below), whose sum is σ = 24360397920. Its totient is φ = 19478624256.

The previous prime is 21851253917. The next prime is 21851254001. The reversal of 21851253943 is 34935215812.

It is a happy number.

It is a cyclic number.

It is not a de Polignac number, because 21851253943 - 2⁵ = 21851253911 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21851253943.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21851253913) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 2138655 + ... + 2148847.

It is an arithmetic number, because the mean of its divisors is an integer number (1522524870).

Almost surely, 2^21851253943 is an apocalyptic number.

21851253943 is a deficient number, since it is larger than the sum of its proper divisors (2509143977).

21851253943 is a wasteful number, since it uses less digits than its factorization.

21851253943 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 16866.

The product of its digits is 259200, while the sum is 43.

The spelling of 21851253943 in words is "twenty-one billion, eight hundred fifty-one million, two hundred fifty-three thousand, nine hundred forty-three".