21997042 has 8 divisors (see below), whose sum is σ = 34060032. Its totient is φ = 10643700.

The previous prime is 21997021. The next prime is 21997043. The reversal of 21997042 is 24079912.

It is a happy number.

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

It is a junction number, because it is equal to n+sod(n) for n = 21996989 and 21997007.

It is not an unprimeable number, because it can be changed into a prime (21997043) 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, 177334 + ... + 177457.

It is an arithmetic number, because the mean of its divisors is an integer number (4257504).

Almost surely, 2^21997042 is an apocalyptic number.

21997042 is a deficient number, since it is larger than the sum of its proper divisors (12062990).

21997042 is a wasteful number, since it uses less digits than its factorization.

21997042 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 354824.

The product of its (nonzero) digits is 9072, while the sum is 34.

The square root of 21997042 is about 4690.1004253640. The cubic root of 21997042 is about 280.1913742718.

The spelling of 21997042 in words is "twenty-one million, nine hundred ninety-seven thousand, forty-two".