65019991 has 4 divisors (see below), whose sum is σ = 65043000. Its totient is φ = 64996984.

The previous prime is 65019979. The next prime is 65020009. The reversal of 65019991 is 19991056.

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

It is a cyclic number.

It is not a de Polignac number, because 65019991 - 2¹⁷ = 64888919 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 (65019971) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 6556 + ... + 13153.

It is an arithmetic number, because the mean of its divisors is an integer number (16260750).

Almost surely, 2^65019991 is an apocalyptic number.

65019991 is a deficient number, since it is larger than the sum of its proper divisors (23009).

65019991 is a wasteful number, since it uses less digits than its factorization.

65019991 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 23008.

The product of its (nonzero) digits is 21870, while the sum is 40.

The square root of 65019991 is about 8063.4974421773. The cubic root of 65019991 is about 402.1137912896.

The spelling of 65019991 in words is "sixty-five million, nineteen thousand, nine hundred ninety-one".