21013760 has 36 divisors (see below), whose sum is σ = 50337588. Its totient is φ = 8404992.

The previous prime is 21013723. The next prime is 21013781. The reversal of 21013760 is 6731012.

It is a happy number.

It can be written as a sum of positive squares in 2 ways, for example, as 6390784 + 14622976 = 2528^2 + 3824^2 .

It is a Harshad number since it is a multiple of its sum of digits (20).

It is a zygodrome in base 4.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 6929 + ... + 9488.

Almost surely, 2^21013760 is an apocalyptic number.

21013760 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21013760 is an abundant number, since it is smaller than the sum of its proper divisors (29323828).

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

21013760 is an equidigital number, since it uses as much as digits as its factorization.

21013760 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 16438 (or 16424 counting only the distinct ones).

The product of its (nonzero) digits is 252, while the sum is 20.

The square root of 21013760 is about 4584.0767881876. The cubic root of 21013760 is about 275.9526628891.

Adding to 21013760 its reverse (6731012), we get a palindrome (27744772).

The spelling of 21013760 in words is "twenty-one million, thirteen thousand, seven hundred sixty".