18147421 has 2 divisors, whose sum is σ = 18147422. Its totient is φ = 18147420.

The previous prime is 18147403. The next prime is 18147457. The reversal of 18147421 is 12474181.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 16695396 + 1452025 = 4086^2 + 1205^2 .

It is an emirp because it is prime and its reverse (12474181) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 18147421 - 2⁷ = 18147293 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 18147421.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (18147401) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9073710 + 9073711.

It is an arithmetic number, because the mean of its divisors is an integer number (9073711).

Almost surely, 2^18147421 is an apocalyptic number.

18147421 is the 2460-th hex number.

It is an amenable number.

18147421 is a deficient number, since it is larger than the sum of its proper divisors (1).

18147421 is an equidigital number, since it uses as much as digits as its factorization.

18147421 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1792, while the sum is 28.

The square root of 18147421 is about 4259.9789905585. The cubic root of 18147421 is about 262.7876622749.

The spelling of 18147421 in words is "eighteen million, one hundred forty-seven thousand, four hundred twenty-one".