66439225961 has 2 divisors, whose sum is σ = 66439225962. Its totient is φ = 66439225960.

The previous prime is 66439225949. The next prime is 66439225967. The reversal of 66439225961 is 16952293466.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 55911439936 + 10527786025 = 236456^2 + 102605^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-66439225961 is a prime.

It is not a weakly prime, because it can be changed into another prime (66439225967) 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, 33219612980 + 33219612981.

It is an arithmetic number, because the mean of its divisors is an integer number (33219612981).

Almost surely, 2^66439225961 is an apocalyptic number.

It is an amenable number.

66439225961 is a deficient number, since it is larger than the sum of its proper divisors (1).

66439225961 is an equidigital number, since it uses as much as digits as its factorization.

66439225961 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 4199040, while the sum is 53.

The spelling of 66439225961 in words is "sixty-six billion, four hundred thirty-nine million, two hundred twenty-five thousand, nine hundred sixty-one".