18948721 has 6 divisors (see below), whose sum is σ = 20828066. Its totient is φ = 17226000.

The previous prime is 18948697. The next prime is 18948733. The reversal of 18948721 is 12784981.

It is a happy number.

It can be written as a sum of positive squares in only one way, i.e., 18879025 + 69696 = 4345^2 + 264^2 .

It is not a de Polignac number, because 18948721 - 2¹⁷ = 18817649 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (18948751) 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, 78180 + ... + 78421.

Almost surely, 2^18948721 is an apocalyptic number.

18948721 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

It is an amenable number.

18948721 is a deficient number, since it is larger than the sum of its proper divisors (1879345).

18948721 is a wasteful number, since it uses less digits than its factorization.

18948721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 156623 (or 156612 counting only the distinct ones).

The product of its digits is 32256, while the sum is 40.

The square root of 18948721 is about 4353.0128646720. The cubic root of 18948721 is about 266.5998907453.

The spelling of 18948721 in words is "eighteen million, nine hundred forty-eight thousand, seven hundred twenty-one".