355721 has 2 divisors, whose sum is σ = 355722. Its totient is φ = 355720.

The previous prime is 355717. The next prime is 355723. The reversal of 355721 is 127553.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 336400 + 19321 = 580^2 + 139^2 .

It is a cyclic number.

It is not a de Polignac number, because 355721 - 2² = 355717 is a prime.

Together with 355723, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (355723) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 177860 + 177861.

It is an arithmetic number, because the mean of its divisors is an integer number (177861).

2³⁵⁵⁷²¹ is an apocalyptic number.

It is an amenable number.

355721 is a deficient number, since it is larger than the sum of its proper divisors (1).

355721 is an equidigital number, since it uses as much as digits as its factorization.

355721 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1050, while the sum is 23.

The square root of 355721 is about 596.4235072497. The cubic root of 355721 is about 70.8548910931.

The spelling of 355721 in words is "three hundred fifty-five thousand, seven hundred twenty-one".