21312445 has 32 divisors (see below), whose sum is σ = 32161536. Its totient is φ = 13171200.

The previous prime is 21312439. The next prime is 21312449. The reversal of 21312445 is 54421312.

It is not a de Polignac number, because 21312445 - 2³ = 21312437 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21312449) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 75705 + ... + 75985.

It is an arithmetic number, because the mean of its divisors is an integer number (1005048).

Almost surely, 2^21312445 is an apocalyptic number.

It is an amenable number.

21312445 is a deficient number, since it is larger than the sum of its proper divisors (10849091).

21312445 is a wasteful number, since it uses less digits than its factorization.

21312445 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 501.

The product of its digits is 960, while the sum is 22.

The square root of 21312445 is about 4616.5403713170. The cubic root of 21312445 is about 277.2539604214.

Adding to 21312445 its reverse (54421312), we get a palindrome (75733757).

The spelling of 21312445 in words is "twenty-one million, three hundred twelve thousand, four hundred forty-five".