81888551 has 4 divisors (see below), whose sum is σ = 83433672. Its totient is φ = 80343432.

The previous prime is 81888529. The next prime is 81888557. The reversal of 81888551 is 15588818.

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 81888551 - 2¹⁰ = 81887527 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81888557) 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, 772481 + ... + 772586.

It is an arithmetic number, because the mean of its divisors is an integer number (20858418).

Almost surely, 2^81888551 is an apocalyptic number.

81888551 is a deficient number, since it is larger than the sum of its proper divisors (1545121).

81888551 is a wasteful number, since it uses less digits than its factorization.

81888551 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1545120.

The product of its digits is 102400, while the sum is 44.

The square root of 81888551 is about 9049.2293042004. The cubic root of 81888551 is about 434.2512349013.

The spelling of 81888551 in words is "eighty-one million, eight hundred eighty-eight thousand, five hundred fifty-one".