18451421 has 2 divisors, whose sum is σ = 18451422. Its totient is φ = 18451420.

The previous prime is 18451403. The next prime is 18451423. The reversal of 18451421 is 12415481.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 14100025 + 4351396 = 3755^2 + 2086^2 .

It is a cyclic number.

It is not a de Polignac number, because 18451421 - 2¹⁴ = 18435037 is a prime.

Together with 18451423, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (18451423) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9225710 + 9225711.

It is an arithmetic number, because the mean of its divisors is an integer number (9225711).

Almost surely, 2^18451421 is an apocalyptic number.

It is an amenable number.

18451421 is a deficient number, since it is larger than the sum of its proper divisors (1).

18451421 is an equidigital number, since it uses as much as digits as its factorization.

18451421 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1280, while the sum is 26.

The square root of 18451421 is about 4295.5117273731. The cubic root of 18451421 is about 264.2469232851.

The spelling of 18451421 in words is "eighteen million, four hundred fifty-one thousand, four hundred twenty-one".