165667421 has 2 divisors, whose sum is σ = 165667422. Its totient is φ = 165667420.

The previous prime is 165667373. The next prime is 165667423. The reversal of 165667421 is 124766561.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 153487321 + 12180100 = 12389^2 + 3490^2 .

It is a cyclic number.

It is not a de Polignac number, because 165667421 - 2⁶ = 165667357 is a prime.

Together with 165667423, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (165667423) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 82833710 + 82833711.

It is an arithmetic number, because the mean of its divisors is an integer number (82833711).

Almost surely, 2^165667421 is an apocalyptic number.

It is an amenable number.

165667421 is a deficient number, since it is larger than the sum of its proper divisors (1).

165667421 is an equidigital number, since it uses as much as digits as its factorization.

165667421 is an evil number, because the sum of its binary digits is even.

The product of its digits is 60480, while the sum is 38.

The square root of 165667421 is about 12871.1856874182. The cubic root of 165667421 is about 549.2191906686.

The spelling of 165667421 in words is "one hundred sixty-five million, six hundred sixty-seven thousand, four hundred twenty-one".