61561765 has 4 divisors (see below), whose sum is σ = 73874124. Its totient is φ = 49249408.

The previous prime is 61561733. The next prime is 61561771. The reversal of 61561765 is 56716516.

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 28579716 + 32982049 = 5346^2 + 5743^2 .

It is a cyclic number.

It is not a de Polignac number, because 61561765 - 2⁵ = 61561733 is a prime.

It is a super-3 number, since 3×61561765³ (a number of 24 digits) contains 333 as substring.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 6156172 + ... + 6156181.

It is an arithmetic number, because the mean of its divisors is an integer number (18468531).

Almost surely, 2^61561765 is an apocalyptic number.

It is an amenable number.

61561765 is a deficient number, since it is larger than the sum of its proper divisors (12312359).

61561765 is a wasteful number, since it uses less digits than its factorization.

61561765 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 12312358.

The product of its digits is 37800, while the sum is 37.

The square root of 61561765 is about 7846.1305750032. The cubic root of 61561765 is about 394.8544354945.

It can be divided in two parts, 61561 and 765, that added together give a palindrome (62326).

The spelling of 61561765 in words is "sixty-one million, five hundred sixty-one thousand, seven hundred sixty-five".