61125781 has 2 divisors, whose sum is σ = 61125782. Its totient is φ = 61125780.

The previous prime is 61125773. The next prime is 61125787. The reversal of 61125781 is 18752116.

61125781 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., 59814756 + 1311025 = 7734^2 + 1145^2 .

It is a cyclic number.

It is not a de Polignac number, because 61125781 - 2³ = 61125773 is a prime.

It is a super-2 number, since 2×61125781² = 7472722205719922, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (61125787) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 30562890 + 30562891.

It is an arithmetic number, because the mean of its divisors is an integer number (30562891).

Almost surely, 2^61125781 is an apocalyptic number.

It is an amenable number.

61125781 is a deficient number, since it is larger than the sum of its proper divisors (1).

61125781 is an equidigital number, since it uses as much as digits as its factorization.

61125781 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 3360, while the sum is 31.

The square root of 61125781 is about 7818.2978326487. The cubic root of 61125781 is about 393.9200989771.

Adding to 61125781 its reverse (18752116), we get a palindrome (79877897).

The spelling of 61125781 in words is "sixty-one million, one hundred twenty-five thousand, seven hundred eighty-one".