81500551 has 8 divisors (see below), whose sum is σ = 89086608. Its totient is φ = 73944000.

The previous prime is 81500521. The next prime is 81500561. The reversal of 81500551 is 15500518.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 81500551 - 2¹¹ = 81498503 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 (81500521) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1380 + ... + 12841.

It is an arithmetic number, because the mean of its divisors is an integer number (11135826).

Almost surely, 2^81500551 is an apocalyptic number.

81500551 is a deficient number, since it is larger than the sum of its proper divisors (7586057).

81500551 is a wasteful number, since it uses less digits than its factorization.

81500551 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 14753.

The product of its (nonzero) digits is 1000, while the sum is 25.

The square root of 81500551 is about 9027.7655596499. The cubic root of 81500551 is about 433.5643000812.

The spelling of 81500551 in words is "eighty-one million, five hundred thousand, five hundred fifty-one".