61640665 has 4 divisors (see below), whose sum is σ = 73968804. Its totient is φ = 49312528.

The previous prime is 61640653. The next prime is 61640669. The reversal of 61640665 is 56604616.

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 6702921 + 54937744 = 2589^2 + 7412^2 .

It is a cyclic number.

It is not a de Polignac number, because 61640665 - 2⁵ = 61640633 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 61640665.

It is not an unprimeable number, because it can be changed into a prime (61640669) 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, 6164062 + ... + 6164071.

It is an arithmetic number, because the mean of its divisors is an integer number (18492201).

Almost surely, 2^61640665 is an apocalyptic number.

It is an amenable number.

61640665 is a deficient number, since it is larger than the sum of its proper divisors (12328139).

61640665 is a wasteful number, since it uses less digits than its factorization.

61640665 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 12328138.

The product of its (nonzero) digits is 25920, while the sum is 34.

The square root of 61640665 is about 7851.1569211168. The cubic root of 61640665 is about 395.0230505162.

The spelling of 61640665 in words is "sixty-one million, six hundred forty thousand, six hundred sixty-five".