21576745 has 4 divisors (see below), whose sum is σ = 25892100. Its totient is φ = 17261392.

The previous prime is 21576743. The next prime is 21576767. The reversal of 21576745 is 54767512.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 14622976 + 6953769 = 3824^2 + 2637^2 .

It is a cyclic number.

It is not a de Polignac number, because 21576745 - 2¹ = 21576743 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21576743) 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, 2157670 + ... + 2157679.

It is an arithmetic number, because the mean of its divisors is an integer number (6473025).

Almost surely, 2^21576745 is an apocalyptic number.

It is an amenable number.

21576745 is a deficient number, since it is larger than the sum of its proper divisors (4315355).

21576745 is an equidigital number, since it uses as much as digits as its factorization.

21576745 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4315354.

The product of its digits is 58800, while the sum is 37.

The square root of 21576745 is about 4645.0775020445. The cubic root of 21576745 is about 278.3953495461.

The spelling of 21576745 in words is "twenty-one million, five hundred seventy-six thousand, seven hundred forty-five".