42121821 has 12 divisors (see below), whose sum is σ = 65332032. Its totient is φ = 24069528.

The previous prime is 42121819. The next prime is 42121843. The reversal of 42121821 is 12812124.

42121821 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is not a de Polignac number, because 42121821 - 2¹ = 42121819 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (21).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (42121621) 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 11 ways as a sum of consecutive naturals, for example, 143125 + ... + 143418.

It is an arithmetic number, because the mean of its divisors is an integer number (5444336).

Almost surely, 2^42121821 is an apocalyptic number.

It is an amenable number.

42121821 is a deficient number, since it is larger than the sum of its proper divisors (23210211).

42121821 is a wasteful number, since it uses less digits than its factorization.

42121821 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 286560 (or 286553 counting only the distinct ones).

The product of its digits is 256, while the sum is 21.

The square root of 42121821 is about 6490.1325872435. The cubic root of 42121821 is about 347.9384139266.

Adding to 42121821 its reverse (12812124), we get a palindrome (54933945).

The spelling of 42121821 in words is "forty-two million, one hundred twenty-one thousand, eight hundred twenty-one".