18961919 has 4 divisors (see below), whose sum is σ = 20077344. Its totient is φ = 17846496.

The previous prime is 18961897. The next prime is 18961933. The reversal of 18961919 is 91916981.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 91916981 = 13 ⋅7070537.

It is a cyclic number.

It is not a de Polignac number, because 18961919 - 2¹² = 18957823 is a prime.

It is a super-2 number, since 2×18961919² = 719108744325122, which contains 22 as substring.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 18961919.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18961939) 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, 557687 + ... + 557720.

It is an arithmetic number, because the mean of its divisors is an integer number (5019336).

Almost surely, 2^18961919 is an apocalyptic number.

18961919 is a deficient number, since it is larger than the sum of its proper divisors (1115425).

18961919 is a wasteful number, since it uses less digits than its factorization.

18961919 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1115424.

The product of its digits is 34992, while the sum is 44.

The square root of 18961919 is about 4354.5285623130. The cubic root of 18961919 is about 266.6617730005.

The spelling of 18961919 in words is "eighteen million, nine hundred sixty-one thousand, nine hundred nineteen".