72405561 has 16 divisors (see below), whose sum is σ = 103019840. Its totient is φ = 45100800.

The previous prime is 72405527. The next prime is 72405563. The reversal of 72405561 is 16550427.

It is not a de Polignac number, because 72405561 - 2⁶ = 72405497 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (72405563) 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 15 ways as a sum of consecutive naturals, for example, 4540 + ... + 12861.

It is an arithmetic number, because the mean of its divisors is an integer number (6438740).

Almost surely, 2^72405561 is an apocalyptic number.

It is an amenable number.

72405561 is a deficient number, since it is larger than the sum of its proper divisors (30614279).

72405561 is a wasteful number, since it uses less digits than its factorization.

72405561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 17496.

The product of its (nonzero) digits is 8400, while the sum is 30.

The square root of 72405561 is about 8509.1457268048. The cubic root of 72405561 is about 416.7964144908.

Adding to 72405561 its reverse (16550427), we get a palindrome (88955988).

The spelling of 72405561 in words is "seventy-two million, four hundred five thousand, five hundred sixty-one".