21706726 has 4 divisors (see below), whose sum is σ = 32560092. Its totient is φ = 10853362.

The previous prime is 21706717. The next prime is 21706777. The reversal of 21706726 is 62760712.

It is a semiprime because it is the product of two primes.

It is a Smith number, since the sum of its digits (31) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5426680 + ... + 5426683.

It is an arithmetic number, because the mean of its divisors is an integer number (8140023).

Almost surely, 2^21706726 is an apocalyptic number.

21706726 is a deficient number, since it is larger than the sum of its proper divisors (10853366).

21706726 is a wasteful number, since it uses less digits than its factorization.

21706726 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10853365.

The product of its (nonzero) digits is 7056, while the sum is 31.

The square root of 21706726 is about 4659.0477567846. The cubic root of 21706726 is about 278.9532601567.

The spelling of 21706726 in words is "twenty-one million, seven hundred six thousand, seven hundred twenty-six".