21455242 has 4 divisors (see below), whose sum is σ = 32182866. Its totient is φ = 10727620.

The previous prime is 21455183. The next prime is 21455257. The reversal of 21455242 is 24255412.

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

It can be written as a sum of positive squares in only one way, i.e., 20784481 + 670761 = 4559^2 + 819^2 .

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 as a sum of consecutive naturals, namely, 5363809 + ... + 5363812.

Almost surely, 2^21455242 is an apocalyptic number.

21455242 is a deficient number, since it is larger than the sum of its proper divisors (10727624).

21455242 is a wasteful number, since it uses less digits than its factorization.

21455242 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10727623.

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

The square root of 21455242 is about 4631.9803540171. The cubic root of 21455242 is about 277.8717987978.

The spelling of 21455242 in words is "twenty-one million, four hundred fifty-five thousand, two hundred forty-two".