18521943890 has 16 divisors (see below), whose sum is σ = 33463442520. Its totient is φ = 7381234560.

The previous prime is 18521943859. The next prime is 18521943917. The reversal of 18521943890 is 9834912581.

It can be written as a sum of positive squares in 4 ways, for example, as 15549840601 + 2972103289 = 124699^2 + 54517^2 .

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 3440051 + ... + 3445430.

Almost surely, 2^18521943890 is an apocalyptic number.

18521943890 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

18521943890 is a deficient number, since it is larger than the sum of its proper divisors (14941498630).

18521943890 is a wasteful number, since it uses less digits than its factorization.

18521943890 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6885757.

The product of its (nonzero) digits is 622080, while the sum is 50.

The spelling of 18521943890 in words is "eighteen billion, five hundred twenty-one million, nine hundred forty-three thousand, eight hundred ninety".