21185629680 has 80 divisors (see below), whose sum is σ = 65847214080. Its totient is φ = 5634726144.

The previous prime is 21185629669. The next prime is 21185629691. The reversal of 21185629680 is 8692658112.

It is an interprime number because it is at equal distance from previous prime (21185629669) and next prime (21185629691).

It is a tau number, because it is divible by the number of its divisors (80).

It is a Harshad number since it is a multiple of its sum of digits (48).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 23320 + ... + 207159.

It is an arithmetic number, because the mean of its divisors is an integer number (823090176).

Almost surely, 2^21185629680 is an apocalyptic number.

21185629680 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 21185629680, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (32923607040).

21185629680 is an abundant number, since it is smaller than the sum of its proper divisors (44661584400).

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

21185629680 is a wasteful number, since it uses less digits than its factorization.

21185629680 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 230878 (or 230872 counting only the distinct ones).

The product of its (nonzero) digits is 414720, while the sum is 48.

The spelling of 21185629680 in words is "twenty-one billion, one hundred eighty-five million, six hundred twenty-nine thousand, six hundred eighty".