61643761 has 2 divisors, whose sum is σ = 61643762. Its totient is φ = 61643760.

The previous prime is 61643759. The next prime is 61643783. The reversal of 61643761 is 16734616.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 57153600 + 4490161 = 7560^2 + 2119^2 .

It is a cyclic number.

It is not a de Polignac number, because 61643761 - 2¹ = 61643759 is a prime.

Together with 61643759, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (61643711) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 30821880 + 30821881.

It is an arithmetic number, because the mean of its divisors is an integer number (30821881).

Almost surely, 2^61643761 is an apocalyptic number.

It is an amenable number.

61643761 is a deficient number, since it is larger than the sum of its proper divisors (1).

61643761 is an equidigital number, since it uses as much as digits as its factorization.

61643761 is an evil number, because the sum of its binary digits is even.

The product of its digits is 18144, while the sum is 34.

The square root of 61643761 is about 7851.3540870349. The cubic root of 61643761 is about 395.0296639582.

The spelling of 61643761 in words is "sixty-one million, six hundred forty-three thousand, seven hundred sixty-one".