18821408 has 12 divisors (see below), whose sum is σ = 37054710. Its totient is φ = 9410688.

The previous prime is 18821399. The next prime is 18821417. The reversal of 18821408 is 80412881.

It is an interprime number because it is at equal distance from previous prime (18821399) and next prime (18821417).

It can be written as a sum of positive squares in only one way, i.e., 15904144 + 2917264 = 3988^2 + 1708^2 .

It is a Harshad number since it is a multiple of its sum of digits (32), and also a Moran number because the ratio is a prime number: 588169 = 18821408 / (1 + 8 + 8 + 2 + 1 + 4 + 0 + 8).

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 294053 + ... + 294116.

Almost surely, 2^18821408 is an apocalyptic number.

It is an amenable number.

18821408 is a deficient number, since it is larger than the sum of its proper divisors (18233302).

18821408 is an equidigital number, since it uses as much as digits as its factorization.

18821408 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 588179 (or 588171 counting only the distinct ones).

The product of its (nonzero) digits is 4096, while the sum is 32.

The square root of 18821408 is about 4338.3646688585. The cubic root of 18821408 is about 266.0014698319.

The spelling of 18821408 in words is "eighteen million, eight hundred twenty-one thousand, four hundred eight".