21390007760 has 80 divisors (see below), whose sum is σ = 54427980672. Its totient is φ = 7753075200.

The previous prime is 21390007759. The next prime is 21390007799. The reversal of 21390007760 is 6770009312.

It is a tau number, because it is divible by the number of its divisors (80).

It is a self number, because there is not a number n which added to its sum of digits gives 21390007760.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 234602 + ... + 312758.

Almost surely, 2^21390007760 is an apocalyptic number.

21390007760 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 21390007760, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (27213990336).

21390007760 is an abundant number, since it is smaller than the sum of its proper divisors (33037972912).

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

21390007760 is a wasteful number, since it uses less digits than its factorization.

21390007760 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 78492 (or 78486 counting only the distinct ones).

The product of its (nonzero) digits is 15876, while the sum is 35.

The spelling of 21390007760 in words is "twenty-one billion, three hundred ninety million, seven thousand, seven hundred sixty".