21013893 has 12 divisors (see below), whose sum is σ = 31400460. Its totient is φ = 13526016.

The previous prime is 21013873. The next prime is 21013907. The reversal of 21013893 is 39831012.

It can be written as a sum of positive squares in 2 ways, for example, as 3849444 + 17164449 = 1962^2 + 4143^2 .

It is not a de Polignac number, because 21013893 - 2¹³ = 21005701 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21013823) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 39996 + ... + 40517.

It is an arithmetic number, because the mean of its divisors is an integer number (2616705).

Almost surely, 2^21013893 is an apocalyptic number.

It is an amenable number.

21013893 is a deficient number, since it is larger than the sum of its proper divisors (10386567).

21013893 is a wasteful number, since it uses less digits than its factorization.

21013893 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 80548 (or 80545 counting only the distinct ones).

The product of its (nonzero) digits is 1296, while the sum is 27.

The square root of 21013893 is about 4584.0912949024. The cubic root of 21013893 is about 275.9532450731.

The spelling of 21013893 in words is "twenty-one million, thirteen thousand, eight hundred ninety-three".