61783721 has 2 divisors, whose sum is σ = 61783722. Its totient is φ = 61783720.

The previous prime is 61783669. The next prime is 61783723. The reversal of 61783721 is 12738716.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 34105600 + 27678121 = 5840^2 + 5261^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-61783721 is a prime.

It is a Sophie Germain prime.

Together with 61783723, it forms a pair of twin primes.

It is a Chen prime.

It is a Curzon number.

It is not a weakly prime, because it can be changed into another prime (61783723) 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, 30891860 + 30891861.

It is an arithmetic number, because the mean of its divisors is an integer number (30891861).

Almost surely, 2^61783721 is an apocalyptic number.

It is an amenable number.

61783721 is a deficient number, since it is larger than the sum of its proper divisors (1).

61783721 is an equidigital number, since it uses as much as digits as its factorization.

61783721 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 14112, while the sum is 35.

The square root of 61783721 is about 7860.2621457557. The cubic root of 61783721 is about 395.3284049832.

The spelling of 61783721 in words is "sixty-one million, seven hundred eighty-three thousand, seven hundred twenty-one".