21688074 has 20 divisors (see below), whose sum is σ = 48597714. Its totient is φ = 7229304.

The previous prime is 21688067. The next prime is 21688109. The reversal of 21688074 is 47088612.

It can be written as a sum of positive squares in only one way, i.e., 17514225 + 4173849 = 4185^2 + 2043^2 .

It is a Curzon number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 9 ways as a sum of consecutive naturals, for example, 66777 + ... + 67100.

Almost surely, 2^21688074 is an apocalyptic number.

21688074 is an abundant number, since it is smaller than the sum of its proper divisors (26909640).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21688074 is a wasteful number, since it uses less digits than its factorization.

21688074 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 133891 (or 133882 counting only the distinct ones).

The product of its (nonzero) digits is 21504, while the sum is 36.

The square root of 21688074 is about 4657.0456300105. The cubic root of 21688074 is about 278.8733382745.

The spelling of 21688074 in words is "twenty-one million, six hundred eighty-eight thousand, seventy-four".