40012561 has 4 divisors (see below), whose sum is σ = 40690800. Its totient is φ = 39334324.

The previous prime is 40012519. The next prime is 40012573. The reversal of 40012561 is 16521004.

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.

It is a cyclic number.

It is not a de Polignac number, because 40012561 - 2²³ = 31623953 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (40012591) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 339031 + ... + 339148.

It is an arithmetic number, because the mean of its divisors is an integer number (10172700).

Almost surely, 2^40012561 is an apocalyptic number.

It is an amenable number.

40012561 is a deficient number, since it is larger than the sum of its proper divisors (678239).

40012561 is an equidigital number, since it uses as much as digits as its factorization.

40012561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 678238.

The product of its (nonzero) digits is 240, while the sum is 19.

The square root of 40012561 is about 6325.5482766318. The cubic root of 40012561 is about 342.0309839352.

Adding to 40012561 its reverse (16521004), we get a palindrome (56533565).

The spelling of 40012561 in words is "forty million, twelve thousand, five hundred sixty-one".