18274721 has 2 divisors, whose sum is σ = 18274722. Its totient is φ = 18274720.

The previous prime is 18274709. The next prime is 18274741. The reversal of 18274721 is 12747281.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 18181696 + 93025 = 4264^2 + 305^2 .

It is an emirp because it is prime and its reverse (12747281) is a distict prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-18274721 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (18274741) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9137360 + 9137361.

It is an arithmetic number, because the mean of its divisors is an integer number (9137361).

Almost surely, 2^18274721 is an apocalyptic number.

It is an amenable number.

18274721 is a deficient number, since it is larger than the sum of its proper divisors (1).

18274721 is an equidigital number, since it uses as much as digits as its factorization.

18274721 is an evil number, because the sum of its binary digits is even.

The product of its digits is 6272, while the sum is 32.

The square root of 18274721 is about 4274.8942676983. The cubic root of 18274721 is about 263.4006961494.

The spelling of 18274721 in words is "eighteen million, two hundred seventy-four thousand, seven hundred twenty-one".