21257366 has 16 divisors (see below), whose sum is σ = 34440000. Its totient is φ = 9782208.

The previous prime is 21257347. The next prime is 21257407. The reversal of 21257366 is 66375212.

It is a congruent number.

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 7 ways as a sum of consecutive naturals, for example, 9635 + ... + 11633.

It is an arithmetic number, because the mean of its divisors is an integer number (2152500).

Almost surely, 2^21257366 is an apocalyptic number.

21257366 is a gapful number since it is divisible by the number (26) formed by its first and last digit.

21257366 is a deficient number, since it is larger than the sum of its proper divisors (13182634).

21257366 is a wasteful number, since it uses less digits than its factorization.

21257366 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2423.

The product of its digits is 15120, while the sum is 32.

The square root of 21257366 is about 4610.5711142981. The cubic root of 21257366 is about 277.0149131583.

The spelling of 21257366 in words is "twenty-one million, two hundred fifty-seven thousand, three hundred sixty-six".