18420261 has 4 divisors (see below), whose sum is σ = 24560352. Its totient is φ = 12280172.

The previous prime is 18420251. The next prime is 18420271. The reversal of 18420261 is 16202481.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 16202481 = 3 ⋅5400827.

It is an interprime number because it is at equal distance from previous prime (18420251) and next prime (18420271).

It is a cyclic number.

It is not a de Polignac number, because 18420261 - 2⁵ = 18420229 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18420221) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3070041 + ... + 3070046.

It is an arithmetic number, because the mean of its divisors is an integer number (6140088).

Almost surely, 2^18420261 is an apocalyptic number.

It is an amenable number.

18420261 is a deficient number, since it is larger than the sum of its proper divisors (6140091).

18420261 is an equidigital number, since it uses as much as digits as its factorization.

18420261 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6140090.

The product of its (nonzero) digits is 768, while the sum is 24.

The square root of 18420261 is about 4291.8831531159. The cubic root of 18420261 is about 264.0980896979.

It can be divided in two parts, 18420 and 261, that added together give a palindrome (18681).

The spelling of 18420261 in words is "eighteen million, four hundred twenty thousand, two hundred sixty-one".