21180006580077 has 20 divisors (see below), whose sum is σ = 31640570165820. Its totient is φ = 14119423740864.

The previous prime is 21180006580049. The next prime is 21180006580079. The reversal of 21180006580077 is 77008560008112.

It is a happy number.

It can be written as a sum of positive squares in 2 ways, for example, as 16268202624996 + 4911803955081 = 4033386^2 + 2216259^2 .

It is a de Polignac number, because none of the positive numbers 2^k-21180006580077 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21180006580079) by changing a digit.

It is a polite number, since it can be written in 19 ways as a sum of consecutive naturals, for example, 3389952 + ... + 7338377.

It is an arithmetic number, because the mean of its divisors is an integer number (1582028508291).

Almost surely, 2^{21180006580077} is an apocalyptic number.

21180006580077 is a gapful number since it is divisible by the number (27) formed by its first and last digit.

It is an amenable number.

21180006580077 is a deficient number, since it is larger than the sum of its proper divisors (10460563585743).

21180006580077 is a wasteful number, since it uses less digits than its factorization.

21180006580077 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10752714 (or 10752705 counting only the distinct ones).

The product of its (nonzero) digits is 188160, while the sum is 45.

Adding to 21180006580077 its reverse (77008560008112), we get a palindrome (98188566588189).

The spelling of 21180006580077 in words is "twenty-one trillion, one hundred eighty billion, six million, five hundred eighty thousand, seventy-seven".