21813608 has 8 divisors (see below), whose sum is σ = 40900530. Its totient is φ = 10906800.

The previous prime is 21813569. The next prime is 21813619. The reversal of 21813608 is 80631812.

It can be written as a sum of positive squares in only one way, i.e., 11303044 + 10510564 = 3362^2 + 3242^2 .

It is a tau number, because it is divible by the number of its divisors (8).

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1363343 + ... + 1363358.

Almost surely, 2^21813608 is an apocalyptic number.

It is an amenable number.

21813608 is a deficient number, since it is larger than the sum of its proper divisors (19086922).

21813608 is a wasteful number, since it uses less digits than its factorization.

21813608 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2726707 (or 2726703 counting only the distinct ones).

The product of its (nonzero) digits is 2304, while the sum is 29.

The square root of 21813608 is about 4670.5040413215. The cubic root of 21813608 is about 279.4103578042.

The spelling of 21813608 in words is "twenty-one million, eight hundred thirteen thousand, six hundred eight".