21815290000 has 225 divisors, whose sum is σ = 61732747791. Its totient is φ = 7444080000.

The previous prime is 21815289989. The next prime is 21815290043. The reversal of 21815290000 is 9251812.

The square root of 21815290000 is 147700.

It is a perfect power (a square), and thus also a powerful number.

It can be written as a sum of positive squares in 2 ways, for example, as 1710318736 + 20104971264 = 41356^2 + 141792^2 .

It is a Harshad number since it is a multiple of its sum of digits (28).

It is a Duffinian number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 44 ways as a sum of consecutive naturals, for example, 103389895 + ... + 103390105.

Almost surely, 2^21815290000 is an apocalyptic number.

21815290000 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

21815290000 is the 147700-th square number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21815290000

21815290000 is an abundant number, since it is smaller than the sum of its proper divisors (39917457791).

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

21815290000 is an frugal number, since it uses more digits than its factorization.

21815290000 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 464 (or 225 counting only the distinct ones).

The product of its (nonzero) digits is 1440, while the sum is 28.

The spelling of 21815290000 in words is "twenty-one billion, eight hundred fifteen million, two hundred ninety thousand".