21715930 has 8 divisors (see below), whose sum is σ = 39088692. Its totient is φ = 8686368.

The previous prime is 21715921. The next prime is 21715931. The reversal of 21715930 is 3951712.

It can be written as a sum of positive squares in 2 ways, for example, as 19456921 + 2259009 = 4411^2 + 1503^2 .

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 (21715931) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1085787 + ... + 1085806.

Almost surely, 2^21715930 is an apocalyptic number.

21715930 is a deficient number, since it is larger than the sum of its proper divisors (17372762).

21715930 is a wasteful number, since it uses less digits than its factorization.

21715930 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2171600.

The product of its (nonzero) digits is 1890, while the sum is 28.

The square root of 21715930 is about 4660.0354075908. The cubic root of 21715930 is about 278.9926814711.

The spelling of 21715930 in words is "twenty-one million, seven hundred fifteen thousand, nine hundred thirty".