18661990 has 16 divisors (see below), whose sum is σ = 35359920. Its totient is φ = 7071840.

The previous prime is 18661963. The next prime is 18661991. The reversal of 18661990 is 9916681.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18661991) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 48921 + ... + 49300.

It is an arithmetic number, because the mean of its divisors is an integer number (2209995).

Almost surely, 2^18661990 is an apocalyptic number.

18661990 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

18661990 is a deficient number, since it is larger than the sum of its proper divisors (16697930).

18661990 is a wasteful number, since it uses less digits than its factorization.

18661990 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 98247.

The product of its (nonzero) digits is 23328, while the sum is 40.

The square root of 18661990 is about 4319.9525460357. The cubic root of 18661990 is about 265.2483254330.

The spelling of 18661990 in words is "eighteen million, six hundred sixty-one thousand, nine hundred ninety".