77075821 has 2 divisors, whose sum is σ = 77075822. Its totient is φ = 77075820.

The previous prime is 77075819. The next prime is 77075839. The reversal of 77075821 is 12857077.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 63282025 + 13793796 = 7955^2 + 3714^2 .

It is an emirp because it is prime and its reverse (12857077) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 77075821 - 2¹ = 77075819 is a prime.

Together with 77075819, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (77075851) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 38537910 + 38537911.

It is an arithmetic number, because the mean of its divisors is an integer number (38537911).

Almost surely, 2^77075821 is an apocalyptic number.

It is an amenable number.

77075821 is a deficient number, since it is larger than the sum of its proper divisors (1).

77075821 is an equidigital number, since it uses as much as digits as its factorization.

77075821 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 27440, while the sum is 37.

The square root of 77075821 is about 8779.2836268115. The cubic root of 77075821 is about 425.5716800372.

The spelling of 77075821 in words is "seventy-seven million, seventy-five thousand, eight hundred twenty-one".