21515420000 has 60 divisors (see below), whose sum is σ = 52931209716. Its totient is φ = 8606160000.

The previous prime is 21515419999. The next prime is 21515420023. The reversal of 21515420000 is 2451512.

It is a Harshad number since it is a multiple of its sum of digits (20).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 9 ways as a sum of consecutive naturals, for example, 517886 + ... + 557885.

Almost surely, 2^21515420000 is an apocalyptic number.

21515420000 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21515420000 is an abundant number, since it is smaller than the sum of its proper divisors (31415789716).

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

21515420000 is an equidigital number, since it uses as much as digits as its factorization.

21515420000 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1075801 (or 1075778 counting only the distinct ones).

The product of its (nonzero) digits is 400, while the sum is 20.

Adding to 21515420000 its reverse (2451512), we get a palindrome (21517871512).

The spelling of 21515420000 in words is "twenty-one billion, five hundred fifteen million, four hundred twenty thousand".