21154320340 has 12 divisors (see below), whose sum is σ = 44424072756. Its totient is φ = 8461728128.

The previous prime is 21154320331. The next prime is 21154320347. The reversal of 21154320340 is 4302345112.

It can be written as a sum of positive squares in 2 ways, for example, as 8934786576 + 12219533764 = 94524^2 + 110542^2 .

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21154320347) 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, 528857989 + ... + 528858028.

It is an arithmetic number, because the mean of its divisors is an integer number (3702006063).

Almost surely, 2^21154320340 is an apocalyptic number.

21154320340 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21154320340 is an abundant number, since it is smaller than the sum of its proper divisors (23269752416).

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

21154320340 is a wasteful number, since it uses less digits than its factorization.

21154320340 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1057716026 (or 1057716024 counting only the distinct ones).

The product of its (nonzero) digits is 2880, while the sum is 25.

Adding to 21154320340 its reverse (4302345112), we get a palindrome (25456665452).

The spelling of 21154320340 in words is "twenty-one billion, one hundred fifty-four million, three hundred twenty thousand, three hundred forty".