61386781 has 2 divisors, whose sum is σ = 61386782. Its totient is φ = 61386780.

The previous prime is 61386769. The next prime is 61386791. The reversal of 61386781 is 18768316.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 45346756 + 16040025 = 6734^2 + 4005^2 .

It is a cyclic number.

It is not a de Polignac number, because 61386781 - 2⁵ = 61386749 is a prime.

It is a super-2 number, since 2×61386781² = 7536673763083922, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (61386751) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 30693390 + 30693391.

It is an arithmetic number, because the mean of its divisors is an integer number (30693391).

Almost surely, 2^61386781 is an apocalyptic number.

It is an amenable number.

61386781 is a deficient number, since it is larger than the sum of its proper divisors (1).

61386781 is an equidigital number, since it uses as much as digits as its factorization.

61386781 is an evil number, because the sum of its binary digits is even.

The product of its digits is 48384, while the sum is 40.

The square root of 61386781 is about 7834.9716655518. The cubic root of 61386781 is about 394.4799672623.

The spelling of 61386781 in words is "sixty-one million, three hundred eighty-six thousand, seven hundred eighty-one".