21013880 has 32 divisors (see below), whose sum is σ = 47993040. Its totient is φ = 8279040.

The previous prime is 21013873. The next prime is 21013907. The reversal of 21013880 is 8831012.

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, 1241 + ... + 6600.

Almost surely, 2^21013880 is an apocalyptic number.

21013880 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21013880 is an abundant number, since it is smaller than the sum of its proper divisors (26979160).

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

21013880 is a wasteful number, since it uses less digits than its factorization.

21013880 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7919 (or 7915 counting only the distinct ones).

The product of its (nonzero) digits is 384, while the sum is 23.

The square root of 21013880 is about 4584.0898769549. The cubic root of 21013880 is about 275.9531881680.

Adding to 21013880 its reverse (8831012), we get a palindrome (29844892).

The spelling of 21013880 in words is "twenty-one million, thirteen thousand, eight hundred eighty".