21939730 has 8 divisors (see below), whose sum is σ = 39491532. Its totient is φ = 8775888.

The previous prime is 21939727. The next prime is 21939733. The reversal of 21939730 is 3793912.

It is an interprime number because it is at equal distance from previous prime (21939727) and next prime (21939733).

It can be written as a sum of positive squares in 2 ways, for example, as 18774889 + 3164841 = 4333^2 + 1779^2 .

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

It is not an unprimeable number, because it can be changed into a prime (21939733) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1096977 + ... + 1096996.

Almost surely, 2^21939730 is an apocalyptic number.

21939730 is a deficient number, since it is larger than the sum of its proper divisors (17551802).

21939730 is a wasteful number, since it uses less digits than its factorization.

21939730 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2193980.

The product of its (nonzero) digits is 10206, while the sum is 34.

The square root of 21939730 is about 4683.9865499380. The cubic root of 21939730 is about 279.9478219099.

The spelling of 21939730 in words is "twenty-one million, nine hundred thirty-nine thousand, seven hundred thirty".