21492857 has 12 divisors (see below), whose sum is σ = 23477220. Its totient is φ = 19649952.

The previous prime is 21492853. The next prime is 21492859. The reversal of 21492857 is 75829412.

It can be written as a sum of positive squares in 2 ways, for example, as 11182336 + 10310521 = 3344^2 + 3211^2 .

It is not a de Polignac number, because 21492857 - 2² = 21492853 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21492857.

It is not an unprimeable number, because it can be changed into a prime (21492853) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 9443 + ... + 11495.

It is an arithmetic number, because the mean of its divisors is an integer number (1956435).

Almost surely, 2^21492857 is an apocalyptic number.

It is an amenable number.

21492857 is a deficient number, since it is larger than the sum of its proper divisors (1984363).

21492857 is a wasteful number, since it uses less digits than its factorization.

21492857 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2120 (or 2101 counting only the distinct ones).

The product of its digits is 40320, while the sum is 38.

The square root of 21492857 is about 4636.0389342627. The cubic root of 21492857 is about 278.0340908454.

The spelling of 21492857 in words is "twenty-one million, four hundred ninety-two thousand, eight hundred fifty-seven".