77803921 has 4 divisors (see below), whose sum is σ = 83788852. Its totient is φ = 71818992.

The previous prime is 77803877. The next prime is 77803969. The reversal of 77803921 is 12930877.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 23619600 + 54184321 = 4860^2 + 7361^2 .

It is a cyclic number.

It is not a de Polignac number, because 77803921 - 2¹⁵ = 77771153 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (77803981) 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 in 3 ways as a sum of consecutive naturals, for example, 2992446 + ... + 2992471.

It is an arithmetic number, because the mean of its divisors is an integer number (20947213).

Almost surely, 2^77803921 is an apocalyptic number.

It is an amenable number.

77803921 is a deficient number, since it is larger than the sum of its proper divisors (5984931).

77803921 is a wasteful number, since it uses less digits than its factorization.

77803921 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5984930.

The product of its (nonzero) digits is 21168, while the sum is 37.

The square root of 77803921 is about 8820.6530937340. The cubic root of 77803921 is about 426.9075426845.

The spelling of 77803921 in words is "seventy-seven million, eight hundred three thousand, nine hundred twenty-one".