16783397581 has 4 divisors (see below), whose sum is σ = 16940251872. Its totient is φ = 16626543292.

The previous prime is 16783397573. The next prime is 16783397627. The reversal of 16783397581 is 18579338761.

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, and also an emirpimes, since its reverse is a distinct semiprime: 18579338761 = 347 ⋅53542763.

It is a cyclic number.

It is not a de Polignac number, because 16783397581 - 2³ = 16783397573 is a prime.

It is a super-2 number, since 2×16783397581² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (16783397531) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 78426985 + ... + 78427198.

It is an arithmetic number, because the mean of its divisors is an integer number (4235062968).

Almost surely, 2^16783397581 is an apocalyptic number.

It is an amenable number.

16783397581 is a deficient number, since it is larger than the sum of its proper divisors (156854291).

16783397581 is a wasteful number, since it uses less digits than its factorization.

16783397581 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 156854290.

The product of its digits is 7620480, while the sum is 58.

The spelling of 16783397581 in words is "sixteen billion, seven hundred eighty-three million, three hundred ninety-seven thousand, five hundred eighty-one".