161421009 has 4 divisors (see below), whose sum is σ = 215228016. Its totient is φ = 107614004.

The previous prime is 161420993. The next prime is 161421041. The reversal of 161421009 is 900124161.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 161421009 - 2⁴ = 161420993 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 161421009.

It is not an unprimeable number, because it can be changed into a prime (161421079) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 26903499 + ... + 26903504.

It is an arithmetic number, because the mean of its divisors is an integer number (53807004).

Almost surely, 2^161421009 is an apocalyptic number.

It is an amenable number.

161421009 is a deficient number, since it is larger than the sum of its proper divisors (53807007).

161421009 is an equidigital number, since it uses as much as digits as its factorization.

161421009 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 53807006.

The product of its (nonzero) digits is 432, while the sum is 24.

The square root of 161421009 is about 12705.1567876985. The cubic root of 161421009 is about 544.4859603386.

The spelling of 161421009 in words is "one hundred sixty-one million, four hundred twenty-one thousand, nine".