18472821 has 4 divisors (see below), whose sum is σ = 24630432. Its totient is φ = 12315212.

The previous prime is 18472789. The next prime is 18472823. The reversal of 18472821 is 12827481.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 18472821 - 2⁵ = 18472789 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18472823) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3078801 + ... + 3078806.

It is an arithmetic number, because the mean of its divisors is an integer number (6157608).

Almost surely, 2^18472821 is an apocalyptic number.

It is an amenable number.

18472821 is a deficient number, since it is larger than the sum of its proper divisors (6157611).

18472821 is an equidigital number, since it uses as much as digits as its factorization.

18472821 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6157610.

The product of its digits is 7168, while the sum is 33.

The square root of 18472821 is about 4298.0019776636. The cubic root of 18472821 is about 264.3490418768.

The spelling of 18472821 in words is "eighteen million, four hundred seventy-two thousand, eight hundred twenty-one".