81790780949 has 4 divisors (see below), whose sum is σ = 81791375436. Its totient is φ = 81790186464.

The previous prime is 81790780931. The next prime is 81790780979. The reversal of 81790780949 is 94908709718.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It can be written as a sum of positive squares in 2 ways, for example, as 10578122500 + 71212658449 = 102850^2 + 266857^2 .

It is a cyclic number.

It is not a de Polignac number, because 81790780949 - 2⁸ = 81790780693 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 81790780891 and 81790780900.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81790780979) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 27107 + ... + 405359.

It is an arithmetic number, because the mean of its divisors is an integer number (20447843859).

Almost surely, 2^81790780949 is an apocalyptic number.

It is an amenable number.

81790780949 is a deficient number, since it is larger than the sum of its proper divisors (594487).

81790780949 is a wasteful number, since it uses less digits than its factorization.

81790780949 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 594486.

The product of its (nonzero) digits is 9144576, while the sum is 62.

The spelling of 81790780949 in words is "eighty-one billion, seven hundred ninety million, seven hundred eighty thousand, nine hundred forty-nine".