42191821 has 16 divisors (see below), whose sum is σ = 51038208. Its totient is φ = 34095600.

The previous prime is 42191791. The next prime is 42191861. The reversal of 42191821 is 12819124.

It is not a de Polignac number, because 42191821 - 2⁵ = 42191789 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 42191821.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (42191861) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 9586 + ... + 13276.

It is an arithmetic number, because the mean of its divisors is an integer number (3189888).

Almost surely, 2^42191821 is an apocalyptic number.

It is an amenable number.

42191821 is a deficient number, since it is larger than the sum of its proper divisors (8846387).

42191821 is a wasteful number, since it uses less digits than its factorization.

42191821 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3792.

The product of its digits is 1152, while the sum is 28.

The square root of 42191821 is about 6495.5231506015. The cubic root of 42191821 is about 348.1310473332.

The spelling of 42191821 in words is "forty-two million, one hundred ninety-one thousand, eight hundred twenty-one".