42609821 has 2 divisors, whose sum is σ = 42609822. Its totient is φ = 42609820.

The previous prime is 42609817. The next prime is 42609857. The reversal of 42609821 is 12890624.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 21724921 + 20884900 = 4661^2 + 4570^2 .

It is a cyclic number.

It is not a de Polignac number, because 42609821 - 2² = 42609817 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (42609811) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 21304910 + 21304911.

It is an arithmetic number, because the mean of its divisors is an integer number (21304911).

Almost surely, 2^42609821 is an apocalyptic number.

It is an amenable number.

42609821 is a deficient number, since it is larger than the sum of its proper divisors (1).

42609821 is an equidigital number, since it uses as much as digits as its factorization.

42609821 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 6912, while the sum is 32.

The square root of 42609821 is about 6527.6198571914. The cubic root of 42609821 is about 349.2769317250.

The spelling of 42609821 in words is "forty-two million, six hundred nine thousand, eight hundred twenty-one".