19905965 has 4 divisors (see below), whose sum is σ = 23887164. Its totient is φ = 15924768.

The previous prime is 19905961. The next prime is 19905979. The reversal of 19905965 is 56950991.

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

It can be written as a sum of positive squares in 2 ways, for example, as 2550409 + 17355556 = 1597^2 + 4166^2 .

It is a cyclic number.

It is not a de Polignac number, because 19905965 - 2² = 19905961 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (19905961) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1990592 + ... + 1990601.

It is an arithmetic number, because the mean of its divisors is an integer number (5971791).

Almost surely, 2^19905965 is an apocalyptic number.

It is an amenable number.

19905965 is a deficient number, since it is larger than the sum of its proper divisors (3981199).

19905965 is an equidigital number, since it uses as much as digits as its factorization.

19905965 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3981198.

The product of its (nonzero) digits is 109350, while the sum is 44.

The square root of 19905965 is about 4461.6101353659. The cubic root of 19905965 is about 271.0156760765.

The spelling of 19905965 in words is "nineteen million, nine hundred five thousand, nine hundred sixty-five".