18307421 has 12 divisors (see below), whose sum is σ = 20416032. Its totient is φ = 16401000.

The previous prime is 18307417. The next prime is 18307423. The reversal of 18307421 is 12470381.

18307421 is nontrivially palindromic in base 5.

It is not a de Polignac number, because 18307421 - 2² = 18307417 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18307423) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 7526 + ... + 9656.

It is an arithmetic number, because the mean of its divisors is an integer number (1701336).

Almost surely, 2^18307421 is an apocalyptic number.

18307421 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

It is an amenable number.

18307421 is a deficient number, since it is larger than the sum of its proper divisors (2108611).

18307421 is a wasteful number, since it uses less digits than its factorization.

18307421 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2224 (or 2213 counting only the distinct ones).

The product of its (nonzero) digits is 1344, while the sum is 26.

The square root of 18307421 is about 4278.7172143062. The cubic root of 18307421 is about 263.5577084963.

The spelling of 18307421 in words is "eighteen million, three hundred seven thousand, four hundred twenty-one".