77990404021 has 4 divisors (see below), whose sum is σ = 79461921132. Its totient is φ = 76518886912.

The previous prime is 77990403983. The next prime is 77990404031. The reversal of 77990404021 is 12040409977.

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 19276267921 + 58714136100 = 138839^2 + 242310^2 .

It is a cyclic number.

It is not a de Polignac number, because 77990404021 - 2¹³ = 77990395829 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (77990404031) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 735758476 + ... + 735758581.

It is an arithmetic number, because the mean of its divisors is an integer number (19865480283).

Almost surely, 2^77990404021 is an apocalyptic number.

It is an amenable number.

77990404021 is a deficient number, since it is larger than the sum of its proper divisors (1471517111).

77990404021 is a wasteful number, since it uses less digits than its factorization.

77990404021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1471517110.

The product of its (nonzero) digits is 127008, while the sum is 43.

The spelling of 77990404021 in words is "seventy-seven billion, nine hundred ninety million, four hundred four thousand, twenty-one".