21077987580 has 432 divisors, whose sum is σ = 72505296864. Its totient is φ = 4949268480.

The previous prime is 21077987563. The next prime is 21077987599. The reversal of 21077987580 is 8578977012.

It is a happy number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 143 ways as a sum of consecutive naturals, for example, 68657787 + ... + 68658093.

Almost surely, 2^21077987580 is an apocalyptic number.

21077987580 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 21077987580, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (36252648432).

21077987580 is an abundant number, since it is smaller than the sum of its proper divisors (51427309284).

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

21077987580 is a wasteful number, since it uses less digits than its factorization.

21077987580 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 446 (or 428 counting only the distinct ones).

The product of its (nonzero) digits is 1975680, while the sum is 54.

The spelling of 21077987580 in words is "twenty-one billion, seventy-seven million, nine hundred eighty-seven thousand, five hundred eighty".