18603721 has 2 divisors, whose sum is σ = 18603722. Its totient is φ = 18603720.

The previous prime is 18603713. The next prime is 18603733. The reversal of 18603721 is 12730681.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 18020025 + 583696 = 4245^2 + 764^2 .

It is a cyclic number.

It is not a de Polignac number, because 18603721 - 2³ = 18603713 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 18603721.

It is not a weakly prime, because it can be changed into another prime (18603701) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9301860 + 9301861.

It is an arithmetic number, because the mean of its divisors is an integer number (9301861).

Almost surely, 2^18603721 is an apocalyptic number.

It is an amenable number.

18603721 is a deficient number, since it is larger than the sum of its proper divisors (1).

18603721 is an equidigital number, since it uses as much as digits as its factorization.

18603721 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 2016, while the sum is 28.

The square root of 18603721 is about 4313.2031021041. The cubic root of 18603721 is about 264.9719728280.

It can be divided in two parts, 1860 and 3721, that multiplied together give a triangular number (6921060 = T₃₇₂₀).

The spelling of 18603721 in words is "eighteen million, six hundred three thousand, seven hundred twenty-one".