81780870391 has 8 divisors (see below), whose sum is σ = 93094429824. Its totient is φ = 71113800120.

The previous prime is 81780870349. The next prime is 81780870407. The reversal of 81780870391 is 19307808718.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 81780870391 - 2⁷ = 81780870263 is a prime.

It is a super-2 number, since 2×81780870391² (a number of 23 digits) contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81780870331) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 161622021 + ... + 161622526.

It is an arithmetic number, because the mean of its divisors is an integer number (11636803728).

Almost surely, 2^81780870391 is an apocalyptic number.

81780870391 is a deficient number, since it is larger than the sum of its proper divisors (11313559433).

81780870391 is a wasteful number, since it uses less digits than its factorization.

81780870391 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 323244581.

The product of its (nonzero) digits is 677376, while the sum is 52.

The spelling of 81780870391 in words is "eighty-one billion, seven hundred eighty million, eight hundred seventy thousand, three hundred ninety-one".