21917044 has 12 divisors (see below), whose sum is σ = 38499300. Its totient is φ = 10917248.

The previous prime is 21917023. The next prime is 21917113. The reversal of 21917044 is 44071912.

It can be written as a sum of positive squares in 2 ways, for example, as 7628644 + 14288400 = 2762^2 + 3780^2 .

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 9109 + ... + 11260.

It is an arithmetic number, because the mean of its divisors is an integer number (3208275).

Almost surely, 2^21917044 is an apocalyptic number.

It is an amenable number.

21917044 is a deficient number, since it is larger than the sum of its proper divisors (16582256).

21917044 is a wasteful number, since it uses less digits than its factorization.

21917044 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 20642 (or 20640 counting only the distinct ones).

The product of its (nonzero) digits is 2016, while the sum is 28.

The square root of 21917044 is about 4681.5642684898. The cubic root of 21917044 is about 279.8512985932.

Adding to 21917044 its reverse (44071912), we get a palindrome (65988956).

The spelling of 21917044 in words is "twenty-one million, nine hundred seventeen thousand, forty-four".