169906421 has 2 divisors, whose sum is σ = 169906422. Its totient is φ = 169906420.

The previous prime is 169906409. The next prime is 169906423. The reversal of 169906421 is 124609961.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 130279396 + 39627025 = 11414^2 + 6295^2 .

It is a cyclic number.

It is not a de Polignac number, because 169906421 - 2⁶ = 169906357 is a prime.

Together with 169906423, 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 (169906423) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 84953210 + 84953211.

It is an arithmetic number, because the mean of its divisors is an integer number (84953211).

Almost surely, 2^169906421 is an apocalyptic number.

It is an amenable number.

169906421 is a deficient number, since it is larger than the sum of its proper divisors (1).

169906421 is an equidigital number, since it uses as much as digits as its factorization.

169906421 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 23328, while the sum is 38.

The square root of 169906421 is about 13034.8157255866. The cubic root of 169906421 is about 553.8641608071.

The spelling of 169906421 in words is "one hundred sixty-nine million, nine hundred six thousand, four hundred twenty-one".