77951381 has 2 divisors, whose sum is σ = 77951382. Its totient is φ = 77951380.

The previous prime is 77951353. The next prime is 77951383. The reversal of 77951381 is 18315977.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 77880625 + 70756 = 8825^2 + 266^2 .

It is an emirp because it is prime and its reverse (18315977) is a distict prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-77951381 is a prime.

It is a super-2 number, since 2×77951381² = 12152835599614322, which contains 22 as substring.

Together with 77951383, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (77951383) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 38975690 + 38975691.

It is an arithmetic number, because the mean of its divisors is an integer number (38975691).

Almost surely, 2^77951381 is an apocalyptic number.

It is an amenable number.

77951381 is a deficient number, since it is larger than the sum of its proper divisors (1).

77951381 is an equidigital number, since it uses as much as digits as its factorization.

77951381 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 52920, while the sum is 41.

The square root of 77951381 is about 8829.0079284142. The cubic root of 77951381 is about 427.1770751917.

The spelling of 77951381 in words is "seventy-seven million, nine hundred fifty-one thousand, three hundred eighty-one".