21185958540 has 24 divisors (see below), whose sum is σ = 59320684080. Its totient is φ = 5649588928.

The previous prime is 21185958529. The next prime is 21185958553. The reversal of 21185958540 is 4585958112.

It is a self number, because there is not a number n which added to its sum of digits gives 21185958540.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 176549595 + ... + 176549714.

It is an arithmetic number, because the mean of its divisors is an integer number (2471695170).

Almost surely, 2^21185958540 is an apocalyptic number.

21185958540 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21185958540 is an abundant number, since it is smaller than the sum of its proper divisors (38134725540).

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

21185958540 is a wasteful number, since it uses less digits than its factorization.

21185958540 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 353099321 (or 353099319 counting only the distinct ones).

The product of its (nonzero) digits is 576000, while the sum is 48.

The spelling of 21185958540 in words is "twenty-one billion, one hundred eighty-five million, nine hundred fifty-eight thousand, five hundred forty".