81555477 has 16 divisors (see below), whose sum is σ = 117817920. Its totient is φ = 49980672.

The previous prime is 81555469. The next prime is 81555497. The reversal of 81555477 is 77455518.

It is not a de Polignac number, because 81555477 - 2³ = 81555469 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81555407) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 16402 + ... + 20787.

It is an arithmetic number, because the mean of its divisors is an integer number (7363620).

Almost surely, 2^81555477 is an apocalyptic number.

It is an amenable number.

81555477 is a deficient number, since it is larger than the sum of its proper divisors (36262443).

81555477 is a wasteful number, since it uses less digits than its factorization.

81555477 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 37252.

The product of its digits is 196000, while the sum is 42.

The square root of 81555477 is about 9030.8071067873. The cubic root of 81555477 is about 433.6616761307.

The spelling of 81555477 in words is "eighty-one million, five hundred fifty-five thousand, four hundred seventy-seven".