18807121 has 2 divisors, whose sum is σ = 18807122. Its totient is φ = 18807120.

The previous prime is 18807091. The next prime is 18807133. The reversal of 18807121 is 12170881.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 13608721 + 5198400 = 3689^2 + 2280^2 .

It is a cyclic number.

It is not a de Polignac number, because 18807121 - 2¹³ = 18798929 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 18807121.

It is not a weakly prime, because it can be changed into another prime (18807161) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9403560 + 9403561.

It is an arithmetic number, because the mean of its divisors is an integer number (9403561).

Almost surely, 2^18807121 is an apocalyptic number.

It is an amenable number.

18807121 is a deficient number, since it is larger than the sum of its proper divisors (1).

18807121 is an equidigital number, since it uses as much as digits as its factorization.

18807121 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 896, while the sum is 28.

The square root of 18807121 is about 4336.7177680822. The cubic root of 18807121 is about 265.9341471144.

The spelling of 18807121 in words is "eighteen million, eight hundred seven thousand, one hundred twenty-one".