61091731565 has 4 divisors (see below), whose sum is σ = 73310077884. Its totient is φ = 48873385248.

The previous prime is 61091731541. The next prime is 61091731579. The reversal of 61091731565 is 56513719016.

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 14576457289 + 46515274276 = 120733^2 + 215674^2 .

It is a cyclic number.

It is not a de Polignac number, because 61091731565 - 2⁶ = 61091731501 is a prime.

It is a super-2 number, since 2×61091731565² (a number of 22 digits) contains 22 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, 6109173152 + ... + 6109173161.

It is an arithmetic number, because the mean of its divisors is an integer number (18327519471).

Almost surely, 2^61091731565 is an apocalyptic number.

It is an amenable number.

61091731565 is a deficient number, since it is larger than the sum of its proper divisors (12218346319).

61091731565 is a wasteful number, since it uses less digits than its factorization.

61091731565 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 12218346318.

The product of its (nonzero) digits is 170100, while the sum is 44.

The spelling of 61091731565 in words is "sixty-one billion, ninety-one million, seven hundred thirty-one thousand, five hundred sixty-five".