21813039 has 24 divisors (see below), whose sum is σ = 33126912. Its totient is φ = 13804560.

The previous prime is 21813037. The next prime is 21813041. The reversal of 21813039 is 93031812.

It is an interprime number because it is at equal distance from previous prime (21813037) and next prime (21813041).

It is not a de Polignac number, because 21813039 - 2¹ = 21813037 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21813037) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 34254 + ... + 34884.

It is an arithmetic number, because the mean of its divisors is an integer number (1380288).

Almost surely, 2^21813039 is an apocalyptic number.

21813039 is a deficient number, since it is larger than the sum of its proper divisors (11313873).

21813039 is a wasteful number, since it uses less digits than its factorization.

21813039 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 827 (or 824 counting only the distinct ones).

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

The square root of 21813039 is about 4670.4431267279. The cubic root of 21813039 is about 279.4079283440.

The spelling of 21813039 in words is "twenty-one million, eight hundred thirteen thousand, thirty-nine".