77493821 has 2 divisors, whose sum is σ = 77493822. Its totient is φ = 77493820.

The previous prime is 77493809. The next prime is 77493827. The reversal of 77493821 is 12839477.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 52041796 + 25452025 = 7214^2 + 5045^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-77493821 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (77493827) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 38746910 + 38746911.

It is an arithmetic number, because the mean of its divisors is an integer number (38746911).

Almost surely, 2^77493821 is an apocalyptic number.

It is an amenable number.

77493821 is a deficient number, since it is larger than the sum of its proper divisors (1).

77493821 is an equidigital number, since it uses as much as digits as its factorization.

77493821 is an evil number, because the sum of its binary digits is even.

The product of its digits is 84672, while the sum is 41.

The square root of 77493821 is about 8803.0574802167. The cubic root of 77493821 is about 426.3396180134.

The spelling of 77493821 in words is "seventy-seven million, four hundred ninety-three thousand, eight hundred twenty-one".