161667421 has 2 divisors, whose sum is σ = 161667422. Its totient is φ = 161667420.

The previous prime is 161667419. The next prime is 161667463. The reversal of 161667421 is 124766161.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 100280196 + 61387225 = 10014^2 + 7835^2 .

It is a cyclic number.

It is not a de Polignac number, because 161667421 - 2¹ = 161667419 is a prime.

It is a super-2 number, since 2×161667421² = 52272710025582482, which contains 22 as substring.

Together with 161667419, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (161667221) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 80833710 + 80833711.

It is an arithmetic number, because the mean of its divisors is an integer number (80833711).

Almost surely, 2^161667421 is an apocalyptic number.

It is an amenable number.

161667421 is a deficient number, since it is larger than the sum of its proper divisors (1).

161667421 is an equidigital number, since it uses as much as digits as its factorization.

161667421 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 12096, while the sum is 34.

The square root of 161667421 is about 12714.8504120182. The cubic root of 161667421 is about 544.7628752690.

The spelling of 161667421 in words is "one hundred sixty-one million, six hundred sixty-seven thousand, four hundred twenty-one".