21080777648 has 240 divisors, whose sum is σ = 52194409344. Its totient is φ = 8190443520.

The previous prime is 21080777617. The next prime is 21080777651. The reversal of 21080777648 is 84677708012.

It is a junction number, because it is equal to n+sod(n) for n = 21080777596 and 21080777605.

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, 45728138 + ... + 45728598.

Almost surely, 2^21080777648 is an apocalyptic number.

21080777648 is a gapful number since it is divisible by the number (28) 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 21080777648, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (26097204672).

21080777648 is an abundant number, since it is smaller than the sum of its proper divisors (31113631696).

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

21080777648 is a wasteful number, since it uses less digits than its factorization.

21080777648 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 620 (or 607 counting only the distinct ones).

The product of its (nonzero) digits is 1053696, while the sum is 50.

The spelling of 21080777648 in words is "twenty-one billion, eighty million, seven hundred seventy-seven thousand, six hundred forty-eight".