18712213 has 4 divisors (see below), whose sum is σ = 20151628. Its totient is φ = 17272800.

The previous prime is 18712201. The next prime is 18712247. The reversal of 18712213 is 31221781.

It is a happy number.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 31221781 = 421 ⋅74161.

It can be written as a sum of positive squares in 2 ways, for example, as 1423249 + 17288964 = 1193^2 + 4158^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-18712213 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 (18712273) 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, 719688 + ... + 719713.

It is an arithmetic number, because the mean of its divisors is an integer number (5037907).

Almost surely, 2^18712213 is an apocalyptic number.

18712213 is a gapful number since it is divisible by the number (13) formed by its first and last digit.

It is an amenable number.

18712213 is a deficient number, since it is larger than the sum of its proper divisors (1439415).

18712213 is a wasteful number, since it uses less digits than its factorization.

18712213 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1439414.

The product of its digits is 672, while the sum is 25.

The square root of 18712213 is about 4325.7615514496. The cubic root of 18712213 is about 265.4860570323.

Adding to 18712213 its reverse (31221781), we get a palindrome (49933994).

The spelling of 18712213 in words is "eighteen million, seven hundred twelve thousand, two hundred thirteen".