21155124280900 has 243 divisors, whose sum is σ = 48873810385701. Its totient is φ = 7947884160000.

The previous prime is 21155124280783. The next prime is 21155124280909. The reversal of 21155124280900 is 908242155112.

It is a happy number.

The square root of 21155124280900 is 4599470.

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

It can be written as a sum of positive squares in 13 ways, for example, as 947869699396 + 20207254581504 = 973586^2 + 4495248^2 .

It is not an unprimeable number, because it can be changed into a prime (21155124280909) by changing a digit.

It is a polite number, since it can be written in 80 ways as a sum of consecutive naturals, for example, 52755920700 + ... + 52755921100.

Almost surely, 2^{21155124280900} is an apocalyptic number.

21155124280900 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

21155124280900 is the 4599470-th square number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21155124280900

21155124280900 is an abundant number, since it is smaller than the sum of its proper divisors (27718686104801).

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

21155124280900 is an equidigital number, since it uses as much as digits as its factorization.

21155124280900 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 952 (or 476 counting only the distinct ones).

The product of its (nonzero) digits is 57600, while the sum is 40.

The spelling of 21155124280900 in words is "twenty-one trillion, one hundred fifty-five billion, one hundred twenty-four million, two hundred eighty thousand, nine hundred".