2165720667 has 64 divisors (see below), whose sum is σ = 3456552960. Its totient is φ = 1192665600.

The previous prime is 2165720659. The next prime is 2165720677. The reversal of 2165720667 is 7660275612.

It is not a de Polignac number, because 2165720667 - 2³ = 2165720659 is a prime.

It is not an unprimeable number, because it can be changed into a prime (2165720647) by changing a digit.

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

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 1096693 + ... + 1098665.

It is an arithmetic number, because the mean of its divisors is an integer number (54008640).

Almost surely, 2^2165720667 is an apocalyptic number.

2165720667 is a deficient number, since it is larger than the sum of its proper divisors (1290832293).

2165720667 is a wasteful number, since it uses less digits than its factorization.

2165720667 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2084.

The product of its (nonzero) digits is 211680, while the sum is 42.

The square root of 2165720667 is about 46537.3040366543. The cubic root of 2165720667 is about 1293.8009935419.

Subtracting 2165720667 from its reverse (7660275612), we obtain a palindrome (5494554945).

It can be divided in two parts, 21657 and 20667, that added together give a palindrome (42324).

The spelling of 2165720667 in words is "two billion, one hundred sixty-five million, seven hundred twenty thousand, six hundred sixty-seven".