61773781 has 2 divisors, whose sum is σ = 61773782. Its totient is φ = 61773780.

The previous prime is 61773773. The next prime is 61773787. The reversal of 61773781 is 18737716.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 57608100 + 4165681 = 7590^2 + 2041^2 .

It is a cyclic number.

It is not a de Polignac number, because 61773781 - 2³ = 61773773 is a prime.

It is a super-2 number, since 2×61773781² = 7632000038071922, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (61773787) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 30886890 + 30886891.

It is an arithmetic number, because the mean of its divisors is an integer number (30886891).

Almost surely, 2^61773781 is an apocalyptic number.

It is an amenable number.

61773781 is a deficient number, since it is larger than the sum of its proper divisors (1).

61773781 is an equidigital number, since it uses as much as digits as its factorization.

61773781 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 49392, while the sum is 40.

The square root of 61773781 is about 7859.6298258887. The cubic root of 61773781 is about 395.3072032004.

The spelling of 61773781 in words is "sixty-one million, seven hundred seventy-three thousand, seven hundred eighty-one".