77945521 has 2 divisors, whose sum is σ = 77945522. Its totient is φ = 77945520.

The previous prime is 77945489. The next prime is 77945579. The reversal of 77945521 is 12554977.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 77440000 + 505521 = 8800^2 + 711^2 .

It is an emirp because it is prime and its reverse (12554977) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 77945521 - 2⁵ = 77945489 is a prime.

It is a super-2 number, since 2×77945521² = 12151008487922882, which contains 22 as substring.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (77945821) 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, 38972760 + 38972761.

It is an arithmetic number, because the mean of its divisors is an integer number (38972761).

Almost surely, 2^77945521 is an apocalyptic number.

It is an amenable number.

77945521 is a deficient number, since it is larger than the sum of its proper divisors (1).

77945521 is an equidigital number, since it uses as much as digits as its factorization.

77945521 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 88200, while the sum is 40.

The square root of 77945521 is about 8828.6760615621. The cubic root of 77945521 is about 427.1663705689.

The spelling of 77945521 in words is "seventy-seven million, nine hundred forty-five thousand, five hundred twenty-one".