345656621 has 2 divisors, whose sum is σ = 345656622. Its totient is φ = 345656620.

The previous prime is 345656593. The next prime is 345656629. The reversal of 345656621 is 126656543.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 336722500 + 8934121 = 18350^2 + 2989^2 .

It is a cyclic number.

It is not a de Polignac number, because 345656621 - 2¹⁴ = 345640237 is a prime.

It is a super-2 number, since 2×345656621² = 238956999282275282, which contains 22 as substring.

It is a Sophie Germain prime.

It is a Chen prime.

It is a Curzon number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (345656629) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 172828310 + 172828311.

It is an arithmetic number, because the mean of its divisors is an integer number (172828311).

Almost surely, 2^345656621 is an apocalyptic number.

It is an amenable number.

345656621 is a deficient number, since it is larger than the sum of its proper divisors (1).

345656621 is an equidigital number, since it uses as much as digits as its factorization.

345656621 is an evil number, because the sum of its binary digits is even.

The product of its digits is 129600, while the sum is 38.

The square root of 345656621 is about 18591.8428618575. The cubic root of 345656621 is about 701.8025793395.

The spelling of 345656621 in words is "three hundred forty-five million, six hundred fifty-six thousand, six hundred twenty-one".