21813356 has 12 divisors (see below), whose sum is σ = 38799600. Its totient is φ = 10727760.

The previous prime is 21813343. The next prime is 21813371. The reversal of 21813356 is 65331812.

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, 44456 + ... + 44943.

It is an arithmetic number, because the mean of its divisors is an integer number (3233300).

Almost surely, 2^21813356 is an apocalyptic number.

It is an amenable number.

21813356 is a deficient number, since it is larger than the sum of its proper divisors (16986244).

21813356 is a wasteful number, since it uses less digits than its factorization.

21813356 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 89464 (or 89462 counting only the distinct ones).

The product of its digits is 4320, while the sum is 29.

The square root of 21813356 is about 4670.4770634272. The cubic root of 21813356 is about 279.4092818446.

The spelling of 21813356 in words is "twenty-one million, eight hundred thirteen thousand, three hundred fifty-six".