81009461 has 4 divisors (see below), whose sum is σ = 87240972. Its totient is φ = 74777952.

The previous prime is 81009457. The next prime is 81009469. The reversal of 81009461 is 16490018.

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

It can be written as a sum of positive squares in 2 ways, for example, as 32706961 + 48302500 = 5719^2 + 6950^2 .

It is a cyclic number.

It is not a de Polignac number, because 81009461 - 2² = 81009457 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81009469) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3115736 + ... + 3115761.

It is an arithmetic number, because the mean of its divisors is an integer number (21810243).

Almost surely, 2^81009461 is an apocalyptic number.

It is an amenable number.

81009461 is a deficient number, since it is larger than the sum of its proper divisors (6231511).

81009461 is a wasteful number, since it uses less digits than its factorization.

81009461 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6231510.

The product of its (nonzero) digits is 1728, while the sum is 29.

The square root of 81009461 is about 9000.5255957638. The cubic root of 81009461 is about 432.6917162675.

Adding to 81009461 its reverse (16490018), we get a palindrome (97499479).

The spelling of 81009461 in words is "eighty-one million, nine thousand, four hundred sixty-one".