21429980 has 96 divisors (see below), whose sum is σ = 54190080. Its totient is φ = 7015680.

The previous prime is 21429937. The next prime is 21430007. The reversal of 21429980 is 8992412.

It is a self number, because there is not a number n which added to its sum of digits gives 21429980.

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, 168677 + ... + 168803.

It is an arithmetic number, because the mean of its divisors is an integer number (564480).

Almost surely, 2^21429980 is an apocalyptic number.

21429980 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 21429980, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (27095040).

21429980 is an abundant number, since it is smaller than the sum of its proper divisors (32760100).

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

21429980 is a wasteful number, since it uses less digits than its factorization.

21429980 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 219 (or 217 counting only the distinct ones).

The product of its (nonzero) digits is 10368, while the sum is 35.

The square root of 21429980 is about 4629.2526394657. The cubic root of 21429980 is about 277.7626979666.

The spelling of 21429980 in words is "twenty-one million, four hundred twenty-nine thousand, nine hundred eighty".