40081561 has 9 divisors (see below), whose sum is σ = 43491231. Its totient is φ = 36922392.

The previous prime is 40081513. The next prime is 40081607. The reversal of 40081561 is 16518004.

The square root of 40081561 is 6331.

It is a perfect power (a square), and thus also a powerful number.

It can be written as a sum of positive squares in only one way, i.e., 5929225 + 34152336 = 2435^2 + 5844^2 .

It is not a de Polignac number, because 40081561 - 2¹¹ = 40079513 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (40081961) by changing a digit.

It is a polite number, since it can be written in 8 ways as a sum of consecutive naturals, for example, 82060 + ... + 82546.

It is an arithmetic number, because the mean of its divisors is an integer number (4832359).

Almost surely, 2^40081561 is an apocalyptic number.

40081561 is the 6331-st square number.

40081561 is the 3166-th centered octagonal number.

It is an amenable number.

40081561 is a deficient number, since it is larger than the sum of its proper divisors (3409670).

40081561 is an frugal number, since it uses more digits than its factorization.

40081561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1000 (or 500 counting only the distinct ones).

The product of its (nonzero) digits is 960, while the sum is 25.

The cubic root of 40081561 is about 342.2274771069.

Multiplying 40081561 by its sum of digits (25), we get a square (1002039025 = 31655²).

Adding to 40081561 its reverse (16518004), we get a palindrome (56599565).

The spelling of 40081561 in words is "forty million, eighty-one thousand, five hundred sixty-one".