661281937 has 2 divisors, whose sum is σ = 661281938. Its totient is φ = 661281936.

The previous prime is 661281923. The next prime is 661281941. The reversal of 661281937 is 739182166.

661281937 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., 655308801 + 5973136 = 25599^2 + 2444^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-661281937 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 661281893 and 661281902.

It is not a weakly prime, because it can be changed into another prime (661281977) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 330640968 + 330640969.

It is an arithmetic number, because the mean of its divisors is an integer number (330640969).

Almost surely, 2^661281937 is an apocalyptic number.

It is an amenable number.

661281937 is a deficient number, since it is larger than the sum of its proper divisors (1).

661281937 is an equidigital number, since it uses as much as digits as its factorization.

661281937 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 108864, while the sum is 43.

The square root of 661281937 is about 25715.4027189931. The cubic root of 661281937 is about 871.2221064098. Note that the first 3 decimals are identical.

The spelling of 661281937 in words is "six hundred sixty-one million, two hundred eighty-one thousand, nine hundred thirty-seven".