21851683540 has 12 divisors (see below), whose sum is σ = 45888535476. Its totient is φ = 8740673408.

The previous prime is 21851683537. The next prime is 21851683547. The reversal of 21851683540 is 4538615812.

It can be written as a sum of positive squares in 2 ways, for example, as 5609710404 + 16241973136 = 74898^2 + 127444^2 .

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21851683547) 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, 546292069 + ... + 546292108.

It is an arithmetic number, because the mean of its divisors is an integer number (3824044623).

Almost surely, 2^21851683540 is an apocalyptic number.

21851683540 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21851683540 is an abundant number, since it is smaller than the sum of its proper divisors (24036851936).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21851683540 is a wasteful number, since it uses less digits than its factorization.

21851683540 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1092584186 (or 1092584184 counting only the distinct ones).

The product of its (nonzero) digits is 230400, while the sum is 43.

The spelling of 21851683540 in words is "twenty-one billion, eight hundred fifty-one million, six hundred eighty-three thousand, five hundred forty".