21251888280 has 288 divisors, whose sum is σ = 80831705760. Its totient is φ = 4743567360.

The previous prime is 21251888267. The next prime is 21251888311. The reversal of 21251888280 is 8288815212.

It is a Harshad number since it is a multiple of its sum of digits (45).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 71 ways as a sum of consecutive naturals, for example, 4657200 + ... + 4661760.

It is an arithmetic number, because the mean of its divisors is an integer number (280665645).

Almost surely, 2^21251888280 is an apocalyptic number.

21251888280 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21251888280, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (40415852880).

21251888280 is an abundant number, since it is smaller than the sum of its proper divisors (59579817480).

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

21251888280 is a wasteful number, since it uses less digits than its factorization.

21251888280 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4671 (or 4621 counting only the distinct ones).

The product of its (nonzero) digits is 163840, while the sum is 45.

The spelling of 21251888280 in words is "twenty-one billion, two hundred fifty-one million, eight hundred eighty-eight thousand, two hundred eighty".