42251809 has 2 divisors, whose sum is σ = 42251810. Its totient is φ = 42251808.

The previous prime is 42251789. The next prime is 42251813. The reversal of 42251809 is 90815224.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 26625600 + 15626209 = 5160^2 + 3953^2 .

It is a cyclic number.

It is not a de Polignac number, because 42251809 - 2⁵ = 42251777 is a prime.

It is not a weakly prime, because it can be changed into another prime (42251899) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 21125904 + 21125905.

It is an arithmetic number, because the mean of its divisors is an integer number (21125905).

Almost surely, 2^42251809 is an apocalyptic number.

It is an amenable number.

42251809 is a deficient number, since it is larger than the sum of its proper divisors (1).

42251809 is an equidigital number, since it uses as much as digits as its factorization.

42251809 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 5760, while the sum is 31.

The square root of 42251809 is about 6500.1391523567. The cubic root of 42251809 is about 348.2959591981.

The spelling of 42251809 in words is "forty-two million, two hundred fifty-one thousand, eight hundred nine".