40642561 has 4 divisors (see below), whose sum is σ = 40659412. Its totient is φ = 40625712.

The previous prime is 40642549. The next prime is 40642571. The reversal of 40642561 is 16524604.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 40564161 + 78400 = 6369^2 + 280^2 .

It is a cyclic number.

It is not a de Polignac number, because 40642561 - 2²³ = 32253953 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (40642571) 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, 4050 + ... + 9883.

It is an arithmetic number, because the mean of its divisors is an integer number (10164853).

Almost surely, 2^40642561 is an apocalyptic number.

It is an amenable number.

40642561 is a deficient number, since it is larger than the sum of its proper divisors (16851).

40642561 is a wasteful number, since it uses less digits than its factorization.

40642561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 16850.

The product of its (nonzero) digits is 5760, while the sum is 28.

The square root of 40642561 is about 6375.1518413290. The cubic root of 40642561 is about 343.8167431394.

The spelling of 40642561 in words is "forty million, six hundred forty-two thousand, five hundred sixty-one".