21506068 has 6 divisors (see below), whose sum is σ = 37635626. Its totient is φ = 10753032.

The previous prime is 21506059. The next prime is 21506083. The reversal of 21506068 is 86060512.

It can be written as a sum of positive squares in only one way, i.e., 19607184 + 1898884 = 4428^2 + 1378^2 .

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 2688255 + ... + 2688262.

Almost surely, 2^21506068 is an apocalyptic number.

It is an amenable number.

21506068 is a deficient number, since it is larger than the sum of its proper divisors (16129558).

21506068 is a wasteful number, since it uses less digits than its factorization.

21506068 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5376521 (or 5376519 counting only the distinct ones).

The product of its (nonzero) digits is 2880, while the sum is 28.

The square root of 21506068 is about 4637.4635308539. The cubic root of 21506068 is about 278.0910455203.

The spelling of 21506068 in words is "twenty-one million, five hundred six thousand, sixty-eight".