77900212021 has 12 divisors (see below), whose sum is σ = 87052256172. Its totient is φ = 69459007104.

The previous prime is 77900211971. The next prime is 77900212031. The reversal of 77900212021 is 12021200977.

It is a happy number.

It can be written as a sum of positive squares in 2 ways, for example, as 36143332996 + 41756879025 = 190114^2 + 204345^2 .

It is not a de Polignac number, because 77900212021 - 2⁹ = 77900211509 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 (77900212031) 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 11 ways as a sum of consecutive naturals, for example, 6340630 + ... + 6352903.

It is an arithmetic number, because the mean of its divisors is an integer number (7254354681).

Almost surely, 2^77900212021 is an apocalyptic number.

It is an amenable number.

77900212021 is a deficient number, since it is larger than the sum of its proper divisors (9152044151).

77900212021 is a wasteful number, since it uses less digits than its factorization.

77900212021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 12693588 (or 12693569 counting only the distinct ones).

The product of its (nonzero) digits is 3528, while the sum is 31.

Adding to 77900212021 its reverse (12021200977), we get a palindrome (89921412998).

The spelling of 77900212021 in words is "seventy-seven billion, nine hundred million, two hundred twelve thousand, twenty-one".