21117018 has 32 divisors (see below), whose sum is σ = 47880000. Its totient is φ = 6155136.

The previous prime is 21117007. The next prime is 21117029. The reversal of 21117018 is 81071112.

It is an interprime number because it is at equal distance from previous prime (21117007) and next prime (21117029).

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 21116985 and 21117003.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 5643 + ... + 8606.

It is an arithmetic number, because the mean of its divisors is an integer number (1496250).

Almost surely, 2^21117018 is an apocalyptic number.

21117018 is an abundant number, since it is smaller than the sum of its proper divisors (26762982).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21117018 is a wasteful number, since it uses less digits than its factorization.

21117018 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 14286.

The product of its (nonzero) digits is 112, while the sum is 21.

The square root of 21117018 is about 4595.3256685462. The cubic root of 21117018 is about 276.4039191929.

The spelling of 21117018 in words is "twenty-one million, one hundred seventeen thousand, eighteen".