66121961 has 2 divisors, whose sum is σ = 66121962. Its totient is φ = 66121960.

The previous prime is 66121933. The next prime is 66121969. The reversal of 66121961 is 16912166.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 55591936 + 10530025 = 7456^2 + 3245^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-66121961 is a prime.

It is a super-2 number, since 2×66121961² = 8744227452971042, which contains 22 as substring.

It is a Chen prime.

It is equal to p_3902936 and since 66121961 and 3902936 have the same sum of digits, it is a Honaker prime.

It is not a weakly prime, because it can be changed into another prime (66121969) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 33060980 + 33060981.

It is an arithmetic number, because the mean of its divisors is an integer number (33060981).

Almost surely, 2^66121961 is an apocalyptic number.

It is an amenable number.

66121961 is a deficient number, since it is larger than the sum of its proper divisors (1).

66121961 is an equidigital number, since it uses as much as digits as its factorization.

66121961 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 3888, while the sum is 32.

The square root of 66121961 is about 8131.5411208454. The cubic root of 66121961 is about 404.3727749878.

It can be divided in two parts, 661 and 21961, that added together give a palindrome (22622).

The spelling of 66121961 in words is "sixty-six million, one hundred twenty-one thousand, nine hundred sixty-one".