345040021 has 2 divisors, whose sum is σ = 345040022. Its totient is φ = 345040020.

The previous prime is 345039991. The next prime is 345040039. The reversal of 345040021 is 120040543.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 342435025 + 2604996 = 18505^2 + 1614^2 .

It is a cyclic number.

It is not a de Polignac number, because 345040021 - 2¹⁵ = 345007253 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (345020021) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 172520010 + 172520011.

It is an arithmetic number, because the mean of its divisors is an integer number (172520011).

Almost surely, 2^345040021 is an apocalyptic number.

It is an amenable number.

345040021 is a deficient number, since it is larger than the sum of its proper divisors (1).

345040021 is an equidigital number, since it uses as much as digits as its factorization.

345040021 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 480, while the sum is 19.

The square root of 345040021 is about 18575.2529188703. The cubic root of 345040021 is about 701.3850271515.

Adding to 345040021 its reverse (120040543), we get a palindrome (465080564).

The spelling of 345040021 in words is "three hundred forty-five million, forty thousand, twenty-one".