81475511 has 4 divisors (see below), whose sum is σ = 87742872. Its totient is φ = 75208152.

The previous prime is 81475507. The next prime is 81475531. The reversal of 81475511 is 11557418.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 81475511 - 2² = 81475507 is a prime.

It is a super-2 number, since 2×81475511² = 13276517785422242, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81475531) 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, 3133661 + ... + 3133686.

It is an arithmetic number, because the mean of its divisors is an integer number (21935718).

Almost surely, 2^81475511 is an apocalyptic number.

81475511 is a deficient number, since it is larger than the sum of its proper divisors (6267361).

81475511 is a wasteful number, since it uses less digits than its factorization.

81475511 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6267360.

The product of its digits is 5600, while the sum is 32.

The square root of 81475511 is about 9026.3786204657. The cubic root of 81475511 is about 433.5198931745.

The spelling of 81475511 in words is "eighty-one million, four hundred seventy-five thousand, five hundred eleven".