21129970680 has 768 divisors, whose sum is σ = 90260352000. Its totient is φ = 4162461696.

The previous prime is 21129970679. The next prime is 21129970709. The reversal of 21129970680 is 8607992112.

21129970680 is a `hidden beast` number, since 211 + 299 + 70 + 6 + 80 = 666.

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 191 ways as a sum of consecutive naturals, for example, 51662316 + ... + 51662724.

It is an arithmetic number, because the mean of its divisors is an integer number (117526500).

Almost surely, 2^21129970680 is an apocalyptic number.

21129970680 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 21129970680, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (45130176000).

21129970680 is an abundant number, since it is smaller than the sum of its proper divisors (69130381320).

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

21129970680 is a wasteful number, since it uses less digits than its factorization.

21129970680 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 548 (or 541 counting only the distinct ones).

The product of its (nonzero) digits is 108864, while the sum is 45.

The spelling of 21129970680 in words is "twenty-one billion, one hundred twenty-nine million, nine hundred seventy thousand, six hundred eighty".