66561437 has 2 divisors, whose sum is σ = 66561438. Its totient is φ = 66561436.

The previous prime is 66561413. The next prime is 66561461. The reversal of 66561437 is 73416566.

It is a happy number.

It is a balanced prime because it is at equal distance from previous prime (66561413) and next prime (66561461).

It can be written as a sum of positive squares in only one way, i.e., 66406201 + 155236 = 8149^2 + 394^2 .

It is a cyclic number.

It is not a de Polignac number, because 66561437 - 2⁶ = 66561373 is a prime.

It is a Chen prime.

It is a self number, because there is not a number n which added to its sum of digits gives 66561437.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (66561037) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 33280718 + 33280719.

It is an arithmetic number, because the mean of its divisors is an integer number (33280719).

Almost surely, 2^66561437 is an apocalyptic number.

It is an amenable number.

66561437 is a deficient number, since it is larger than the sum of its proper divisors (1).

66561437 is an equidigital number, since it uses as much as digits as its factorization.

66561437 is an evil number, because the sum of its binary digits is even.

The product of its digits is 90720, while the sum is 38.

The square root of 66561437 is about 8158.5192896751. The cubic root of 66561437 is about 405.2666779936.

The spelling of 66561437 in words is "sixty-six million, five hundred sixty-one thousand, four hundred thirty-seven".