42865621 has 2 divisors, whose sum is σ = 42865622. Its totient is φ = 42865620.

The previous prime is 42865579. The next prime is 42865639. The reversal of 42865621 is 12656824.

42865621 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 31203396 + 11662225 = 5586^2 + 3415^2 .

It is a cyclic number.

It is not a de Polignac number, because 42865621 - 2¹⁹ = 42341333 is a prime.

It is a super-2 number, since 2×42865621² = 3674922927431282, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (42865651) 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 as a sum of consecutive naturals, namely, 21432810 + 21432811.

It is an arithmetic number, because the mean of its divisors is an integer number (21432811).

Almost surely, 2^42865621 is an apocalyptic number.

It is an amenable number.

42865621 is a deficient number, since it is larger than the sum of its proper divisors (1).

42865621 is an equidigital number, since it uses as much as digits as its factorization.

42865621 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 23040, while the sum is 34.

The square root of 42865621 is about 6547.1842039155. The cubic root of 42865621 is about 349.9744770504.

It can be divided in two parts, 428 and 65621, that added together give a square (66049 = 257²).

The spelling of 42865621 in words is "forty-two million, eight hundred sixty-five thousand, six hundred twenty-one".