17942021 has 4 divisors (see below), whose sum is σ = 18997452. Its totient is φ = 16886592.

The previous prime is 17942017. The next prime is 17942053. The reversal of 17942021 is 12024971.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 12024971 = 7 ⋅1717853.

It can be written as a sum of positive squares in 2 ways, for example, as 6477025 + 11464996 = 2545^2 + 3386^2 .

It is a cyclic number.

It is not a de Polignac number, because 17942021 - 2² = 17942017 is a prime.

It is a super-2 number, since 2×17942021² = 643832235128882, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (17942011) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 527690 + ... + 527723.

It is an arithmetic number, because the mean of its divisors is an integer number (4749363).

Almost surely, 2^17942021 is an apocalyptic number.

It is an amenable number.

17942021 is a deficient number, since it is larger than the sum of its proper divisors (1055431).

17942021 is a wasteful number, since it uses less digits than its factorization.

17942021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1055430.

The product of its (nonzero) digits is 1008, while the sum is 26.

The square root of 17942021 is about 4235.8022852820. The cubic root of 17942021 is about 261.7924516391.

Adding to 17942021 its reverse (12024971), we get a palindrome (29966992).

The spelling of 17942021 in words is "seventeen million, nine hundred forty-two thousand, twenty-one".