77136421 has 2 divisors, whose sum is σ = 77136422. Its totient is φ = 77136420.

The previous prime is 77136413. The next prime is 77136443. The reversal of 77136421 is 12463177.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 76212900 + 923521 = 8730^2 + 961^2 .

It is an emirp because it is prime and its reverse (12463177) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 77136421 - 2³ = 77136413 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (77136121) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 38568210 + 38568211.

It is an arithmetic number, because the mean of its divisors is an integer number (38568211).

Almost surely, 2^77136421 is an apocalyptic number.

It is an amenable number.

77136421 is a deficient number, since it is larger than the sum of its proper divisors (1).

77136421 is an equidigital number, since it uses as much as digits as its factorization.

77136421 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 7056, while the sum is 31.

The square root of 77136421 is about 8782.7342553444. The cubic root of 77136421 is about 425.6831844730.

Adding to 77136421 its reverse (12463177), we get a palindrome (89599598).

The spelling of 77136421 in words is "seventy-seven million, one hundred thirty-six thousand, four hundred twenty-one".