81339551 has 8 divisors (see below), whose sum is σ = 85804800. Its totient is φ = 76892760.

The previous prime is 81339529. The next prime is 81339553. The reversal of 81339551 is 15593318.

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 81339551 - 2¹⁰ = 81338527 is a prime.

It is a super-2 number, since 2×81339551² = 13232245113763202, 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 (81339553) 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, 4970 + ... + 13688.

It is an arithmetic number, because the mean of its divisors is an integer number (10725600).

Almost surely, 2^81339551 is an apocalyptic number.

81339551 is a deficient number, since it is larger than the sum of its proper divisors (4465249).

81339551 is a wasteful number, since it uses less digits than its factorization.

81339551 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9229.

The product of its digits is 16200, while the sum is 35.

The square root of 81339551 is about 9018.8442164171. The cubic root of 81339551 is about 433.2786174833.

The spelling of 81339551 in words is "eighty-one million, three hundred thirty-nine thousand, five hundred fifty-one".