81540901 has 8 divisors (see below), whose sum is σ = 87978744. Its totient is φ = 75126720.

The previous prime is 81540889. The next prime is 81540929. The reversal of 81540901 is 10904518.

It is a happy number.

It is a Cunningham number, because it is equal to 9030²+1.

It can be written as a sum of positive squares in 4 ways, for example, as 7150276 + 74390625 = 2674^2 + 8625^2 .

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 81540901 - 2¹⁷ = 81409829 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 81540901.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81540961) 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, 1611 + ... + 12871.

It is an arithmetic number, because the mean of its divisors is an integer number (10997343).

Almost surely, 2^81540901 is an apocalyptic number.

It is an amenable number.

81540901 is a deficient number, since it is larger than the sum of its proper divisors (6437843).

81540901 is a wasteful number, since it uses less digits than its factorization.

81540901 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 11831.

The product of its (nonzero) digits is 1440, while the sum is 28.

The square root of 81540901 is about 9030.0000553710. Note that the first 4 decimals coincide. The cubic root of 81540901 is about 433.6358392017.

The spelling of 81540901 in words is "eighty-one million, five hundred forty thousand, nine hundred one".