18503921 has 4 divisors (see below), whose sum is σ = 18518772. Its totient is φ = 18489072.

The previous prime is 18503911. The next prime is 18503951. The reversal of 18503921 is 12930581.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 16313521 + 2190400 = 4039^2 + 1480^2 .

It is a cyclic number.

It is not a de Polignac number, because 18503921 - 2⁶ = 18503857 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (18503911) 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, 5366 + ... + 8111.

It is an arithmetic number, because the mean of its divisors is an integer number (4629693).

Almost surely, 2^18503921 is an apocalyptic number.

It is an amenable number.

18503921 is a deficient number, since it is larger than the sum of its proper divisors (14851).

18503921 is a wasteful number, since it uses less digits than its factorization.

18503921 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 14850.

The product of its (nonzero) digits is 2160, while the sum is 29.

The square root of 18503921 is about 4301.6184163638. The cubic root of 18503921 is about 264.4973073721.

The spelling of 18503921 in words is "eighteen million, five hundred three thousand, nine hundred twenty-one".