21004997760 has 512 divisors, whose sum is σ = 77283360000. Its totient is φ = 5455392768.

The previous prime is 21004997759. The next prime is 21004997773. The reversal of 21004997760 is 6779940012.

It is a Harshad number since it is a multiple of its sum of digits (45).

It is an unprimeable number.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 60186066 + ... + 60186414.

Almost surely, 2^21004997760 is an apocalyptic number.

21004997760 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 21004997760, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (38641680000).

21004997760 is an abundant number, since it is smaller than the sum of its proper divisors (56278362240).

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

21004997760 is an frugal number, since it uses more digits than its factorization.

21004997760 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 432 (or 402 counting only the distinct ones).

The product of its (nonzero) digits is 190512, while the sum is 45.

The spelling of 21004997760 in words is "twenty-one billion, four million, nine hundred ninety-seven thousand, seven hundred sixty".