21718370 has 8 divisors (see below), whose sum is σ = 39093084. Its totient is φ = 8687344.

The previous prime is 21718369. The next prime is 21718381. The reversal of 21718370 is 7381712.

It can be written as a sum of positive squares in 2 ways, for example, as 20638849 + 1079521 = 4543^2 + 1039^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a Curzon number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1085909 + ... + 1085928.

Almost surely, 2^21718370 is an apocalyptic number.

21718370 is a deficient number, since it is larger than the sum of its proper divisors (17374714).

21718370 is a wasteful number, since it uses less digits than its factorization.

21718370 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2171844.

The product of its (nonzero) digits is 2352, while the sum is 29.

The square root of 21718370 is about 4660.2972008231. The cubic root of 21718370 is about 279.0031302775.

The spelling of 21718370 in words is "twenty-one million, seven hundred eighteen thousand, three hundred seventy".