21032306 has 4 divisors (see below), whose sum is σ = 31548462. Its totient is φ = 10516152.

The previous prime is 21032299. The next prime is 21032309. The reversal of 21032306 is 60323012.

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., 19492225 + 1540081 = 4415^2 + 1241^2 .

It is not an unprimeable number, because it can be changed into a prime (21032309) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5258075 + ... + 5258078.

Almost surely, 2^21032306 is an apocalyptic number.

21032306 is a deficient number, since it is larger than the sum of its proper divisors (10516156).

21032306 is a wasteful number, since it uses less digits than its factorization.

21032306 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10516155.

The product of its (nonzero) digits is 216, while the sum is 17.

The square root of 21032306 is about 4586.0992139290. The cubic root of 21032306 is about 276.0338210322.

Adding to 21032306 its reverse (60323012), we get a palindrome (81355318).

The spelling of 21032306 in words is "twenty-one million, thirty-two thousand, three hundred six".