66721037 has 2 divisors, whose sum is σ = 66721038. Its totient is φ = 66721036.

The previous prime is 66721001. The next prime is 66721087. The reversal of 66721037 is 73012766.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 62315236 + 4405801 = 7894^2 + 2099^2 .

It is a cyclic number.

It is not a de Polignac number, because 66721037 - 2¹² = 66716941 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 66720994 and 66721012.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (66721087) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 33360518 + 33360519.

It is an arithmetic number, because the mean of its divisors is an integer number (33360519).

Almost surely, 2^66721037 is an apocalyptic number.

It is an amenable number.

66721037 is a deficient number, since it is larger than the sum of its proper divisors (1).

66721037 is an equidigital number, since it uses as much as digits as its factorization.

66721037 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 10584, while the sum is 32.

The square root of 66721037 is about 8168.2946200538. The cubic root of 66721037 is about 405.5903335354.

The spelling of 66721037 in words is "sixty-six million, seven hundred twenty-one thousand, thirty-seven".