18121636 has 48 divisors (see below), whose sum is σ = 36091440. Its totient is φ = 7902720.

The previous prime is 18121633. The next prime is 18121651. The reversal of 18121636 is 63612181.

It can be written as a sum of positive squares in 8 ways, for example, as 481636 + 17640000 = 694^2 + 4200^2 .

It is an alternating number because its digits alternate between odd and even.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18121633) 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, 91890 + ... + 92086.

It is an arithmetic number, because the mean of its divisors is an integer number (751905).

Almost surely, 2^18121636 is an apocalyptic number.

It is an amenable number.

18121636 is a deficient number, since it is larger than the sum of its proper divisors (17969804).

18121636 is a wasteful number, since it uses less digits than its factorization.

18121636 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 304 (or 302 counting only the distinct ones).

The product of its digits is 1728, while the sum is 28.

The square root of 18121636 is about 4256.9514913844. The cubic root of 18121636 is about 262.6631415207.

The spelling of 18121636 in words is "eighteen million, one hundred twenty-one thousand, six hundred thirty-six".