21399261600 has 144 divisors (see below), whose sum is σ = 69823343520. Its totient is φ = 5692646400.

The previous prime is 21399261599. The next prime is 21399261619. The reversal of 21399261600 is 616299312.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 999811 + ... + 1020989.

It is an arithmetic number, because the mean of its divisors is an integer number (484884330).

Almost surely, 2^21399261600 is an apocalyptic number.

21399261600 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 21399261600, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (34911671760).

21399261600 is an abundant number, since it is smaller than the sum of its proper divisors (48424081920).

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

21399261600 is a wasteful number, since it uses less digits than its factorization.

21399261600 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 21623 (or 21610 counting only the distinct ones).

The product of its (nonzero) digits is 34992, while the sum is 39.

The spelling of 21399261600 in words is "twenty-one billion, three hundred ninety-nine million, two hundred sixty-one thousand, six hundred".