21255442 has 16 divisors (see below), whose sum is σ = 34480152. Its totient is φ = 9768960.

The previous prime is 21255439. The next prime is 21255449. The reversal of 21255442 is 24455212.

It can be written as a sum of positive squares in 4 ways, for example, as 16152361 + 5103081 = 4019^2 + 2259^2 .

It is not an unprimeable number, because it can be changed into a prime (21255449) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 5092 + ... + 8272.

Almost surely, 2^21255442 is an apocalyptic number.

21255442 is a deficient number, since it is larger than the sum of its proper divisors (13224710).

21255442 is a wasteful number, since it uses less digits than its factorization.

21255442 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3453.

The product of its digits is 3200, while the sum is 25.

The square root of 21255442 is about 4610.3624586360. The cubic root of 21255442 is about 277.0065553845.

The spelling of 21255442 in words is "twenty-one million, two hundred fifty-five thousand, four hundred forty-two".