77869921 has 2 divisors, whose sum is σ = 77869922. Its totient is φ = 77869920.

The previous prime is 77869873. The next prime is 77869931. The reversal of 77869921 is 12996877.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 69488896 + 8381025 = 8336^2 + 2895^2 .

It is a cyclic number.

It is not a de Polignac number, because 77869921 - 2¹⁷ = 77738849 is a prime.

It is not a weakly prime, because it can be changed into another prime (77869931) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 38934960 + 38934961.

It is an arithmetic number, because the mean of its divisors is an integer number (38934961).

Almost surely, 2^77869921 is an apocalyptic number.

It is an amenable number.

77869921 is a deficient number, since it is larger than the sum of its proper divisors (1).

77869921 is an equidigital number, since it uses as much as digits as its factorization.

77869921 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 381024, while the sum is 49.

The square root of 77869921 is about 8824.3935202370. The cubic root of 77869921 is about 427.0282218402.

The spelling of 77869921 in words is "seventy-seven million, eight hundred sixty-nine thousand, nine hundred twenty-one".