81038551 has 4 divisors (see below), whose sum is σ = 88405704. Its totient is φ = 73671400.

The previous prime is 81038549. The next prime is 81038569. The reversal of 81038551 is 15583018.

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

It is not a de Polignac number, because 81038551 - 2¹ = 81038549 is a prime.

It is a Smith number, since the sum of its digits (31) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81038521) 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, 3683560 + ... + 3683581.

It is an arithmetic number, because the mean of its divisors is an integer number (22101426).

Almost surely, 2^81038551 is an apocalyptic number.

81038551 is a deficient number, since it is larger than the sum of its proper divisors (7367153).

81038551 is a wasteful number, since it uses less digits than its factorization.

81038551 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7367152.

The product of its (nonzero) digits is 4800, while the sum is 31.

The square root of 81038551 is about 9002.1414674510. The cubic root of 81038551 is about 432.7435023821.

The spelling of 81038551 in words is "eighty-one million, thirty-eight thousand, five hundred fifty-one".