21261736 has 16 divisors (see below), whose sum is σ = 39967200. Its totient is φ = 10603824.

The previous prime is 21261707. The next prime is 21261767. The reversal of 21261736 is 63716212.

It is a super-2 number, since 2×21261736² = 904122835467392, which contains 22 as substring.

It is an unprimeable number.

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, 181 + ... + 6523.

It is an arithmetic number, because the mean of its divisors is an integer number (2497950).

Almost surely, 2^21261736 is an apocalyptic number.

It is an amenable number.

21261736 is a deficient number, since it is larger than the sum of its proper divisors (18705464).

21261736 is a wasteful number, since it uses less digits than its factorization.

21261736 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6768 (or 6764 counting only the distinct ones).

The product of its digits is 3024, while the sum is 28.

The square root of 21261736 is about 4611.0450008648. The cubic root of 21261736 is about 277.0338943784.

Adding to 21261736 its reverse (63716212), we get a palindrome (84977948).

The spelling of 21261736 in words is "twenty-one million, two hundred sixty-one thousand, seven hundred thirty-six".