161906399 has 4 divisors (see below), whose sum is σ = 165351264. Its totient is φ = 158461536.

The previous prime is 161906389. The next prime is 161906411. The reversal of 161906399 is 993609161.

It is a happy number.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-161906399 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (161906369) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1722362 + ... + 1722455.

It is an arithmetic number, because the mean of its divisors is an integer number (41337816).

Almost surely, 2^161906399 is an apocalyptic number.

161906399 is a deficient number, since it is larger than the sum of its proper divisors (3444865).

161906399 is an equidigital number, since it uses as much as digits as its factorization.

161906399 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3444864.

The product of its (nonzero) digits is 78732, while the sum is 44.

The square root of 161906399 is about 12724.2445355314. The cubic root of 161906399 is about 545.0311673111.

The spelling of 161906399 in words is "one hundred sixty-one million, nine hundred six thousand, three hundred ninety-nine".