66951415981 has 2 divisors, whose sum is σ = 66951415982. Its totient is φ = 66951415980.

The previous prime is 66951415961. The next prime is 66951415987. The reversal of 66951415981 is 18951415966.

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., 40338714025 + 26612701956 = 200845^2 + 163134^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-66951415981 is a prime.

It is a super-2 number, since 2×66951415981² (a number of 22 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (66951415987) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 33475707990 + 33475707991.

It is an arithmetic number, because the mean of its divisors is an integer number (33475707991).

Almost surely, 2^66951415981 is an apocalyptic number.

It is an amenable number.

66951415981 is a deficient number, since it is larger than the sum of its proper divisors (1).

66951415981 is an equidigital number, since it uses as much as digits as its factorization.

66951415981 is an evil number, because the sum of its binary digits is even.

The product of its digits is 2332800, while the sum is 55.

The spelling of 66951415981 in words is "sixty-six billion, nine hundred fifty-one million, four hundred fifteen thousand, nine hundred eighty-one".