21723386 has 4 divisors (see below), whose sum is σ = 32585082. Its totient is φ = 10861692.

The previous prime is 21723379. The next prime is 21723389. The reversal of 21723386 is 68332712.

It is a happy number.

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., 17901361 + 3822025 = 4231^2 + 1955^2 .

It is a Curzon number.

It is a plaindrome in base 13.

It is not an unprimeable number, because it can be changed into a prime (21723389) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5430845 + ... + 5430848.

Almost surely, 2^21723386 is an apocalyptic number.

21723386 is a deficient number, since it is larger than the sum of its proper divisors (10861696).

21723386 is a wasteful number, since it uses less digits than its factorization.

21723386 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10861695.

The product of its digits is 12096, while the sum is 32.

The square root of 21723386 is about 4660.8353328561. The cubic root of 21723386 is about 279.0246078251.

The spelling of 21723386 in words is "twenty-one million, seven hundred twenty-three thousand, three hundred eighty-six".