77605921 has 2 divisors, whose sum is σ = 77605922. Its totient is φ = 77605920.

The previous prime is 77605919. The next prime is 77605961. The reversal of 77605921 is 12950677.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 76317696 + 1288225 = 8736^2 + 1135^2 .

It is a cyclic number.

It is not a de Polignac number, because 77605921 - 2¹ = 77605919 is a prime.

Together with 77605919, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (77605961) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 38802960 + 38802961.

It is an arithmetic number, because the mean of its divisors is an integer number (38802961).

Almost surely, 2^77605921 is an apocalyptic number.

It is an amenable number.

77605921 is a deficient number, since it is larger than the sum of its proper divisors (1).

77605921 is an equidigital number, since it uses as much as digits as its factorization.

77605921 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 26460, while the sum is 37.

The square root of 77605921 is about 8809.4222852580. The cubic root of 77605921 is about 426.5450952328.

The spelling of 77605921 in words is "seventy-seven million, six hundred five thousand, nine hundred twenty-one".