21155042 has 8 divisors (see below), whose sum is σ = 31894236. Its totient is φ = 10523632.

The previous prime is 21155041. The next prime is 21155053. The reversal of 21155042 is 24055112.

It can be written as a sum of positive squares in 2 ways, for example, as 20620681 + 534361 = 4541^2 + 731^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is not an unprimeable number, because it can be changed into a prime (21155041) 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 3 ways as a sum of consecutive naturals, for example, 26453 + ... + 27240.

Almost surely, 2^21155042 is an apocalyptic number.

21155042 is a deficient number, since it is larger than the sum of its proper divisors (10739194).

21155042 is a wasteful number, since it uses less digits than its factorization.

21155042 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 53892.

The product of its (nonzero) digits is 400, while the sum is 20.

The square root of 21155042 is about 4599.4610553846. The cubic root of 21155042 is about 276.5697203920.

The spelling of 21155042 in words is "twenty-one million, one hundred fifty-five thousand, forty-two".