21373760 has 56 divisors (see below), whose sum is σ = 53903880. Its totient is φ = 8044544.

The previous prime is 21373717. The next prime is 21373771. The reversal of 21373760 is 6737312.

21373760 = 153² + 154² + ... + 407².

It can be written as a sum of positive squares in 4 ways, for example, as 1517824 + 19855936 = 1232^2 + 4456^2 .

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 3476 + ... + 7404.

Almost surely, 2^21373760 is an apocalyptic number.

21373760 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 21373760, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (26951940).

21373760 is an abundant number, since it is smaller than the sum of its proper divisors (32530120).

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

21373760 is a wasteful number, since it uses less digits than its factorization.

21373760 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3963 (or 3953 counting only the distinct ones).

The product of its (nonzero) digits is 5292, while the sum is 29.

The square root of 21373760 is about 4623.1763972403. The cubic root of 21373760 is about 277.5195884774.

The spelling of 21373760 in words is "twenty-one million, three hundred seventy-three thousand, seven hundred sixty".