18742021 has 2 divisors, whose sum is σ = 18742022. Its totient is φ = 18742020.

The previous prime is 18741979. The next prime is 18742051. The reversal of 18742021 is 12024781.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 17556100 + 1185921 = 4190^2 + 1089^2 .

It is a cyclic number.

It is not a de Polignac number, because 18742021 - 2⁷ = 18741893 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (18742051) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9371010 + 9371011.

It is an arithmetic number, because the mean of its divisors is an integer number (9371011).

Almost surely, 2^18742021 is an apocalyptic number.

It is an amenable number.

18742021 is a deficient number, since it is larger than the sum of its proper divisors (1).

18742021 is an equidigital number, since it uses as much as digits as its factorization.

18742021 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 25.

The square root of 18742021 is about 4329.2055853239. The cubic root of 18742021 is about 265.6269527146.

The spelling of 18742021 in words is "eighteen million, seven hundred forty-two thousand, twenty-one".