21249719280 has 160 divisors (see below), whose sum is σ = 73728763200. Its totient is φ = 5625151488.

The previous prime is 21249719273. The next prime is 21249719303. The reversal of 21249719280 is 8291794212.

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 31 ways as a sum of consecutive naturals, for example, 260016 + ... + 331824.

It is an arithmetic number, because the mean of its divisors is an integer number (460804770).

Almost surely, 2^21249719280 is an apocalyptic number.

21249719280 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 21249719280, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (36864381600).

21249719280 is an abundant number, since it is smaller than the sum of its proper divisors (52479043920).

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

21249719280 is a wasteful number, since it uses less digits than its factorization.

21249719280 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 71968 (or 71956 counting only the distinct ones).

The product of its (nonzero) digits is 145152, while the sum is 45.

The spelling of 21249719280 in words is "twenty-one billion, two hundred forty-nine million, seven hundred nineteen thousand, two hundred eighty".