77721893 has 2 divisors, whose sum is σ = 77721894. Its totient is φ = 77721892.

The previous prime is 77721883. The next prime is 77721923. The reversal of 77721893 is 39812777.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 50452609 + 27269284 = 7103^2 + 5222^2 .

It is a cyclic number.

It is not a de Polignac number, because 77721893 - 2¹⁰ = 77720869 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (77721803) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 38860946 + 38860947.

It is an arithmetic number, because the mean of its divisors is an integer number (38860947).

Almost surely, 2^77721893 is an apocalyptic number.

It is an amenable number.

77721893 is a deficient number, since it is larger than the sum of its proper divisors (1).

77721893 is an equidigital number, since it uses as much as digits as its factorization.

77721893 is an evil number, because the sum of its binary digits is even.

The product of its digits is 148176, while the sum is 44.

The square root of 77721893 is about 8816.0020984571. The cubic root of 77721893 is about 426.7574616209.

The spelling of 77721893 in words is "seventy-seven million, seven hundred twenty-one thousand, eight hundred ninety-three".