18357993 has 6 divisors (see below), whose sum is σ = 26517114. Its totient is φ = 12238656.

The previous prime is 18357961. The next prime is 18358001. The reversal of 18357993 is 39975381.

It is a happy number.

It can be written as a sum of positive squares in only one way, i.e., 12938409 + 5419584 = 3597^2 + 2328^2 .

It is not a de Polignac number, because 18357993 - 2⁵ = 18357961 is a prime.

It is not an unprimeable number, because it can be changed into a prime (18357923) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 1019880 + ... + 1019897.

It is an arithmetic number, because the mean of its divisors is an integer number (4419519).

Almost surely, 2^18357993 is an apocalyptic number.

It is an amenable number.

18357993 is a deficient number, since it is larger than the sum of its proper divisors (8159121).

18357993 is a wasteful number, since it uses less digits than its factorization.

18357993 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2039783 (or 2039780 counting only the distinct ones).

The product of its digits is 204120, while the sum is 45.

The square root of 18357993 is about 4284.6228538811. The cubic root of 18357993 is about 263.8001673026.

The spelling of 18357993 in words is "eighteen million, three hundred fifty-seven thousand, nine hundred ninety-three".