81211563 has 24 divisors (see below), whose sum is σ = 120826992. Its totient is φ = 52532928.

The previous prime is 81211523. The next prime is 81211573. The reversal of 81211563 is 36511218.

81211563 is a `hidden beast` number, since 81 + 21 + 1 + 563 = 666.

It is not a de Polignac number, because 81211563 - 2⁸ = 81211307 is a prime.

It is not an unprimeable number, because it can be changed into a prime (81211523) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 66345 + ... + 67557.

It is an arithmetic number, because the mean of its divisors is an integer number (5034458).

Almost surely, 2^81211563 is an apocalyptic number.

81211563 is a deficient number, since it is larger than the sum of its proper divisors (39615429).

81211563 is a wasteful number, since it uses less digits than its factorization.

81211563 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1435 (or 1432 counting only the distinct ones).

The product of its digits is 1440, while the sum is 27.

The square root of 81211563 is about 9011.7458352974. The cubic root of 81211563 is about 433.0512431643.

The spelling of 81211563 in words is "eighty-one million, two hundred eleven thousand, five hundred sixty-three".