21939706 has 4 divisors (see below), whose sum is σ = 32909562. Its totient is φ = 10969852.

The previous prime is 21939703. The next prime is 21939713. The reversal of 21939706 is 60793912.

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

It can be written as a sum of positive squares in only one way, i.e., 21390625 + 549081 = 4625^2 + 741^2 .

It is not an unprimeable number, because it can be changed into a prime (21939703) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5484925 + ... + 5484928.

Almost surely, 2^21939706 is an apocalyptic number.

21939706 is a deficient number, since it is larger than the sum of its proper divisors (10969856).

21939706 is a wasteful number, since it uses less digits than its factorization.

21939706 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10969855.

The product of its (nonzero) digits is 20412, while the sum is 37.

The square root of 21939706 is about 4683.9839880170. The cubic root of 21939706 is about 279.9477198310.

The spelling of 21939706 in words is "twenty-one million, nine hundred thirty-nine thousand, seven hundred six".