61251505561 has 4 divisors (see below), whose sum is σ = 61312942372. Its totient is φ = 61190068752.

The previous prime is 61251505559. The next prime is 61251505591. The reversal of 61251505561 is 16550515216.

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 24757134336 + 36494371225 = 157344^2 + 191035^2 .

It is a cyclic number.

It is not a de Polignac number, because 61251505561 - 2¹ = 61251505559 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 61251505561.

It is not an unprimeable number, because it can be changed into a prime (61251505541) 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, 30716910 + ... + 30718903.

It is an arithmetic number, because the mean of its divisors is an integer number (15328235593).

Almost surely, 2^61251505561 is an apocalyptic number.

It is an amenable number.

61251505561 is a deficient number, since it is larger than the sum of its proper divisors (61436811).

61251505561 is an equidigital number, since it uses as much as digits as its factorization.

61251505561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 61436810.

The product of its (nonzero) digits is 45000, while the sum is 37.

The spelling of 61251505561 in words is "sixty-one billion, two hundred fifty-one million, five hundred five thousand, five hundred sixty-one".