21046257 has 16 divisors (see below), whose sum is σ = 32256000. Its totient is φ = 13546512.

The previous prime is 21046253. The next prime is 21046273. The reversal of 21046257 is 75264012.

It is not a de Polignac number, because 21046257 - 2² = 21046253 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a self number, because there is not a number n which added to its sum of digits gives 21046257.

It is not an unprimeable number, because it can be changed into a prime (21046253) by changing a digit.

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 15 ways as a sum of consecutive naturals, for example, 12657 + ... + 14222.

It is an arithmetic number, because the mean of its divisors is an integer number (2016000).

Almost surely, 2^21046257 is an apocalyptic number.

21046257 is a gapful number since it is divisible by the number (27) formed by its first and last digit.

It is an amenable number.

21046257 is a deficient number, since it is larger than the sum of its proper divisors (11209743).

21046257 is a wasteful number, since it uses less digits than its factorization.

21046257 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 26917 (or 26911 counting only the distinct ones).

The product of its (nonzero) digits is 3360, while the sum is 27.

The square root of 21046257 is about 4587.6199711833. The cubic root of 21046257 is about 276.0948398079.

The spelling of 21046257 in words is "twenty-one million, forty-six thousand, two hundred fifty-seven".