21117390 has 32 divisors (see below), whose sum is σ = 57922560. Its totient is φ = 4826784.

The previous prime is 21117377. The next prime is 21117391. The reversal of 21117390 is 9371112.

It is a self number, because there is not a number n which added to its sum of digits gives 21117390.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21117391) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 50070 + ... + 50489.

It is an arithmetic number, because the mean of its divisors is an integer number (1810080).

Almost surely, 2^21117390 is an apocalyptic number.

21117390 is an abundant number, since it is smaller than the sum of its proper divisors (36805170).

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

21117390 is a wasteful number, since it uses less digits than its factorization.

21117390 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 100576.

The product of its (nonzero) digits is 378, while the sum is 24.

The square root of 21117390 is about 4595.3661442806. The cubic root of 21117390 is about 276.4055422385.

The spelling of 21117390 in words is "twenty-one million, one hundred seventeen thousand, three hundred ninety".