18220387 has 2 divisors, whose sum is σ = 18220388. Its totient is φ = 18220386.

The previous prime is 18220361. The next prime is 18220403. The reversal of 18220387 is 78302281.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-18220387 is a prime.

It is not a weakly prime, because it can be changed into another prime (18220337) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9110193 + 9110194.

It is an arithmetic number, because the mean of its divisors is an integer number (9110194).

Almost surely, 2^18220387 is an apocalyptic number.

18220387 is a deficient number, since it is larger than the sum of its proper divisors (1).

18220387 is an equidigital number, since it uses as much as digits as its factorization.

18220387 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 5376, while the sum is 31.

The square root of 18220387 is about 4268.5345260405. The cubic root of 18220387 is about 263.1393912836.

The spelling of 18220387 in words is "eighteen million, two hundred twenty thousand, three hundred eighty-seven".