21492785 has 4 divisors (see below), whose sum is σ = 25791348. Its totient is φ = 17194224.

The previous prime is 21492749. The next prime is 21492791. The reversal of 21492785 is 58729412.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 7661824 + 13830961 = 2768^2 + 3719^2 .

It is a cyclic number.

It is not a de Polignac number, because 21492785 - 2¹⁰ = 21491761 is a prime.

It is an alternating number because its digits alternate between even and odd.

It is a Duffinian 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 3 ways as a sum of consecutive naturals, for example, 2149274 + ... + 2149283.

It is an arithmetic number, because the mean of its divisors is an integer number (6447837).

Almost surely, 2^21492785 is an apocalyptic number.

It is an amenable number.

21492785 is a deficient number, since it is larger than the sum of its proper divisors (4298563).

21492785 is an equidigital number, since it uses as much as digits as its factorization.

21492785 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4298562.

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

The square root of 21492785 is about 4636.0311690065. The cubic root of 21492785 is about 278.0337803783.

The spelling of 21492785 in words is "twenty-one million, four hundred ninety-two thousand, seven hundred eighty-five".