19845021 has 32 divisors (see below), whose sum is σ = 31868928. Its totient is φ = 10739520.

The previous prime is 19845011. The next prime is 19845029. The reversal of 19845021 is 12054891.

It is a happy number.

It is not a de Polignac number, because 19845021 - 2⁵ = 19844989 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 19845021.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (19845029) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 87310 + ... + 87536.

It is an arithmetic number, because the mean of its divisors is an integer number (995904).

Almost surely, 2^19845021 is an apocalyptic number.

It is an amenable number.

19845021 is a deficient number, since it is larger than the sum of its proper divisors (12023907).

19845021 is a wasteful number, since it uses less digits than its factorization.

19845021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 441.

The product of its (nonzero) digits is 2880, while the sum is 30.

The square root of 19845021 is about 4454.7750784972. The cubic root of 19845021 is about 270.7388132704.

The spelling of 19845021 in words is "nineteen million, eight hundred forty-five thousand, twenty-one".