21551716 has 12 divisors (see below), whose sum is σ = 39934188. Its totient is φ = 10141952.

The previous prime is 21551701. The next prime is 21551737. The reversal of 21551716 is 61715512.

It can be written as a sum of positive squares in 2 ways, for example, as 6760000 + 14791716 = 2600^2 + 3846^2 .

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, 158401 + ... + 158536.

It is an arithmetic number, because the mean of its divisors is an integer number (3327849).

Almost surely, 2^21551716 is an apocalyptic number.

It is an amenable number.

21551716 is a deficient number, since it is larger than the sum of its proper divisors (18382472).

21551716 is a wasteful number, since it uses less digits than its factorization.

21551716 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 316958 (or 316956 counting only the distinct ones).

The product of its digits is 2100, while the sum is 28.

The square root of 21551716 is about 4642.3825779442. The cubic root of 21551716 is about 278.2876617984.

The spelling of 21551716 in words is "twenty-one million, five hundred fifty-one thousand, seven hundred sixteen".