81405207 has 12 divisors (see below), whose sum is σ = 126630504. Its totient is φ = 50095440.

The previous prime is 81405193. The next prime is 81405209. The reversal of 81405207 is 70250418.

It is not a de Polignac number, because 81405207 - 2¹¹ = 81403159 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81405209) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 347769 + ... + 348002.

It is an arithmetic number, because the mean of its divisors is an integer number (10552542).

Almost surely, 2^81405207 is an apocalyptic number.

81405207 is a deficient number, since it is larger than the sum of its proper divisors (45225297).

81405207 is a wasteful number, since it uses less digits than its factorization.

81405207 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 695790 (or 695787 counting only the distinct ones).

The product of its (nonzero) digits is 2240, while the sum is 27.

The square root of 81405207 is about 9022.4834164436. The cubic root of 81405207 is about 433.3951646813.

The spelling of 81405207 in words is "eighty-one million, four hundred five thousand, two hundred seven".