66981919 has 2 divisors, whose sum is σ = 66981920. Its totient is φ = 66981918.

The previous prime is 66981899. The next prime is 66981931. The reversal of 66981919 is 91918966.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-66981919 is a prime.

It is a super-2 number, since 2×66981919² = 8973154945845122, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (66921919) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 33490959 + 33490960.

It is an arithmetic number, because the mean of its divisors is an integer number (33490960).

Almost surely, 2^66981919 is an apocalyptic number.

66981919 is a deficient number, since it is larger than the sum of its proper divisors (1).

66981919 is an equidigital number, since it uses as much as digits as its factorization.

66981919 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 209952, while the sum is 49.

The square root of 66981919 is about 8184.2482244859. The cubic root of 66981919 is about 406.1182710106.

The spelling of 66981919 in words is "sixty-six million, nine hundred eighty-one thousand, nine hundred nineteen".