16542021 has 4 divisors (see below), whose sum is σ = 22056032. Its totient is φ = 11028012.

The previous prime is 16542017. The next prime is 16542023. The reversal of 16542021 is 12024561.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is not a de Polignac number, because 16542021 - 2² = 16542017 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (16542023) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2757001 + ... + 2757006.

It is an arithmetic number, because the mean of its divisors is an integer number (5514008).

Almost surely, 2^16542021 is an apocalyptic number.

It is an amenable number.

16542021 is a deficient number, since it is larger than the sum of its proper divisors (5514011).

16542021 is an equidigital number, since it uses as much as digits as its factorization.

16542021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5514010.

The product of its (nonzero) digits is 480, while the sum is 21.

The square root of 16542021 is about 4067.1883408566. The cubic root of 16542021 is about 254.7981023955.

Adding to 16542021 its reverse (12024561), we get a palindrome (28566582).

The spelling of 16542021 in words is "sixteen million, five hundred forty-two thousand, twenty-one".