19940161 has 4 divisors (see below), whose sum is σ = 20583424. Its totient is φ = 19296900.

The previous prime is 19940159. The next prime is 19940191. The reversal of 19940161 is 16104991.

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 19940161 - 2¹ = 19940159 is a prime.

It is a super-2 number, since 2×19940161² = 795220041411842, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (31), and also a Moran number because the ratio is a prime number: 643231 = 19940161 / (1 + 9 + 9 + 4 + 0 + 1 + 6 + 1).

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (19940131) 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, 321585 + ... + 321646.

It is an arithmetic number, because the mean of its divisors is an integer number (5145856).

Almost surely, 2^19940161 is an apocalyptic number.

It is an amenable number.

19940161 is a deficient number, since it is larger than the sum of its proper divisors (643263).

19940161 is an equidigital number, since it uses as much as digits as its factorization.

19940161 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 643262.

The product of its (nonzero) digits is 1944, while the sum is 31.

The square root of 19940161 is about 4465.4407397255. The cubic root of 19940161 is about 271.1707778299.

The spelling of 19940161 in words is "nineteen million, nine hundred forty thousand, one hundred sixty-one".