21706238 has 8 divisors (see below), whose sum is σ = 32654232. Its totient is φ = 10821496.

The previous prime is 21706211. The next prime is 21706241. The reversal of 21706238 is 83260712.

It is a happy number.

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

It is a super-2 number, since 2×21706238² = 942321536225288, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 21706238.

It is a congruent 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, 14945 + ... + 16332.

It is an arithmetic number, because the mean of its divisors is an integer number (4081779).

Almost surely, 2^21706238 is an apocalyptic number.

21706238 is a deficient number, since it is larger than the sum of its proper divisors (10947994).

21706238 is a wasteful number, since it uses less digits than its factorization.

21706238 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 31626.

The product of its (nonzero) digits is 4032, while the sum is 29.

The square root of 21706238 is about 4658.9953852735. The cubic root of 21706238 is about 278.9511697108.

The spelling of 21706238 in words is "twenty-one million, seven hundred six thousand, two hundred thirty-eight".