21090512 has 10 divisors (see below), whose sum is σ = 40862898. Its totient is φ = 10545248.

The previous prime is 21090497. The next prime is 21090529. The reversal of 21090512 is 21509012.

It can be written as a sum of positive squares in only one way, i.e., 17106496 + 3984016 = 4136^2 + 1996^2 .

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 659063 + ... + 659094.

Almost surely, 2^21090512 is an apocalyptic number.

It is an amenable number.

21090512 is a deficient number, since it is larger than the sum of its proper divisors (19772386).

21090512 is a wasteful number, since it uses less digits than its factorization.

21090512 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1318165 (or 1318159 counting only the distinct ones).

The product of its (nonzero) digits is 180, while the sum is 20.

The square root of 21090512 is about 4592.4407453989. The cubic root of 21090512 is about 276.2882237261.

Adding to 21090512 its reverse (21509012), we get a palindrome (42599524).

The spelling of 21090512 in words is "twenty-one million, ninety thousand, five hundred twelve".