19191919 has 16 divisors (see below), whose sum is σ = 20832480. Its totient is φ = 17625600.

The previous prime is 19191917. The next prime is 19191923. The reversal of 19191919 is 91919191.

19191919 is nontrivially palindromic in base 11.

It is a cyclic number.

It is not a de Polignac number, because 19191919 - 2¹ = 19191917 is a prime.

It is a super-2 number, since 2×19191919² = 736659509805122, which contains 22 as substring.

It is a Duffinian number.

19191919 is an undulating number in base 10.

19191919 is a modest number, since divided by 191919 gives 19 as remainder.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (19191911) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is an upside-down number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 140019 + ... + 140155.

It is an arithmetic number, because the mean of its divisors is an integer number (1302030).

Almost surely, 2^19191919 is an apocalyptic number.

19191919 is a gapful number since it is divisible by the number (19) formed by its first and last digit.

19191919 is a deficient number, since it is larger than the sum of its proper divisors (1640561).

19191919 is a wasteful number, since it uses less digits than its factorization.

With its successor (19191920) it forms a Ruth-Aaron pair, since the sum of their prime factors is the same (330).

19191919 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 330.

The product of its digits is 6561, while the sum is 40.

The square root of 19191919 is about 4380.8582492475. The cubic root of 19191919 is about 267.7356074856.

The spelling of 19191919 in words is "nineteen million, one hundred ninety-one thousand, nine hundred nineteen".