21251588 has 6 divisors (see below), whose sum is σ = 37190286. Its totient is φ = 10625792.

The previous prime is 21251543. The next prime is 21251597. The reversal of 21251588 is 88515212.

It is a happy number.

It can be written as a sum of positive squares in only one way, i.e., 17572864 + 3678724 = 4192^2 + 1918^2 .

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, 2656445 + ... + 2656452.

It is an arithmetic number, because the mean of its divisors is an integer number (6198381).

Almost surely, 2^21251588 is an apocalyptic number.

It is an amenable number.

21251588 is a deficient number, since it is larger than the sum of its proper divisors (15938698).

21251588 is a wasteful number, since it uses less digits than its factorization.

21251588 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5312901 (or 5312899 counting only the distinct ones).

The product of its digits is 6400, while the sum is 32.

The square root of 21251588 is about 4609.9444682122. The cubic root of 21251588 is about 276.9898122559.

The spelling of 21251588 in words is "twenty-one million, two hundred fifty-one thousand, five hundred eighty-eight".