21069778520 has 192 divisors, whose sum is σ = 56572162560. Its totient is φ = 7038662400.

The previous prime is 21069778511. The next prime is 21069778573. The reversal of 21069778520 is 2587796012.

It is a happy number.

It is a Harshad number since it is a multiple of its sum of digits (47).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 30491375 + ... + 30492065.

It is an arithmetic number, because the mean of its divisors is an integer number (294646680).

Almost surely, 2^21069778520 is an apocalyptic number.

21069778520 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 21069778520, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (28286081280).

21069778520 is an abundant number, since it is smaller than the sum of its proper divisors (35502384040).

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

21069778520 is a wasteful number, since it uses less digits than its factorization.

21069778520 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1094 (or 1083 counting only the distinct ones).

The product of its (nonzero) digits is 423360, while the sum is 47.

The spelling of 21069778520 in words is "twenty-one billion, sixty-nine million, seven hundred seventy-eight thousand, five hundred twenty".