42678821 has 4 divisors (see below), whose sum is σ = 42721644. Its totient is φ = 42636000.

The previous prime is 42678781. The next prime is 42678859. The reversal of 42678821 is 12887624.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 8584900 + 34093921 = 2930^2 + 5839^2 .

It is a cyclic number.

It is not a de Polignac number, because 42678821 - 2¹⁴ = 42662437 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (42671821) 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, 19880 + ... + 21921.

It is an arithmetic number, because the mean of its divisors is an integer number (10680411).

Almost surely, 2^42678821 is an apocalyptic number.

It is an amenable number.

42678821 is a deficient number, since it is larger than the sum of its proper divisors (42823).

42678821 is a wasteful number, since it uses less digits than its factorization.

42678821 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 42822.

The product of its digits is 43008, while the sum is 38.

The square root of 42678821 is about 6532.9029535116. The cubic root of 42678821 is about 349.4653633323.

The spelling of 42678821 in words is "forty-two million, six hundred seventy-eight thousand, eight hundred twenty-one".