81376952405 has 64 divisors (see below), whose sum is σ = 118792396800. Its totient is φ = 52274315520.

The previous prime is 81376952399. The next prime is 81376952417. The reversal of 81376952405 is 50425967318.

81376952405 = T₃₉₃₁₈ + T₃₉₃₁₉ + ... + T₃₉₄₂₂.

It is a happy number.

It is not a de Polignac number, because 81376952405 - 2¹² = 81376948309 is a prime.

It is a Curzon number.

It is a congruent number.

It is an unprimeable number.

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 63 ways as a sum of consecutive naturals, for example, 53855600 + ... + 53857110.

It is an arithmetic number, because the mean of its divisors is an integer number (1856131200).

It is a 2-persistent number, because it is pandigital, and so is 2⋅81376952405 = 162753904810, but 3⋅81376952405 = 244130857215 is not.

Almost surely, 2^81376952405 is an apocalyptic number.

81376952405 is the 164699-th octagonal number.

It is an amenable number.

81376952405 is a deficient number, since it is larger than the sum of its proper divisors (37415444395).

81376952405 is a wasteful number, since it uses less digits than its factorization.

81376952405 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2394.

The product of its (nonzero) digits is 1814400, while the sum is 50.

The spelling of 81376952405 in words is "eighty-one billion, three hundred seventy-six million, nine hundred fifty-two thousand, four hundred five".