18772221 has 16 divisors (see below), whose sum is σ = 27129536. Its totient is φ = 11477376.

The previous prime is 18772183. The next prime is 18772277. The reversal of 18772221 is 12227781.

It is a happy number.

It is not a de Polignac number, because 18772221 - 2⁶ = 18772157 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18772291) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 4881 + ... + 7833.

It is an arithmetic number, because the mean of its divisors is an integer number (1695596).

Almost surely, 2^18772221 is an apocalyptic number.

It is an amenable number.

18772221 is a deficient number, since it is larger than the sum of its proper divisors (8357315).

18772221 is a wasteful number, since it uses less digits than its factorization.

18772221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3132.

The product of its digits is 3136, while the sum is 30.

The square root of 18772221 is about 4332.6921192256. The cubic root of 18772221 is about 265.7695490245.

The spelling of 18772221 in words is "eighteen million, seven hundred seventy-two thousand, two hundred twenty-one".