61663250821 has 2 divisors, whose sum is σ = 61663250822. Its totient is φ = 61663250820.

The previous prime is 61663250791. The next prime is 61663250843. The reversal of 61663250821 is 12805236616.

61663250821 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 54575968225 + 7087282596 = 233615^2 + 84186^2 .

It is a cyclic number.

It is not a de Polignac number, because 61663250821 - 2¹⁵ = 61663218053 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (61663200821) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 30831625410 + 30831625411.

It is an arithmetic number, because the mean of its divisors is an integer number (30831625411).

Almost surely, 2^61663250821 is an apocalyptic number.

It is an amenable number.

61663250821 is a deficient number, since it is larger than the sum of its proper divisors (1).

61663250821 is an equidigital number, since it uses as much as digits as its factorization.

61663250821 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 103680, while the sum is 40.

The spelling of 61663250821 in words is "sixty-one billion, six hundred sixty-three million, two hundred fifty thousand, eight hundred twenty-one".