81402261 has 16 divisors (see below), whose sum is σ = 113557248. Its totient is φ = 51814400.

The previous prime is 81402259. The next prime is 81402317. The reversal of 81402261 is 16220418.

81402261 = 1389² + 1390² + ... + 1429².

It is a cyclic number.

It is not a de Polignac number, because 81402261 - 2¹ = 81402259 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81402361) 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 15 ways as a sum of consecutive naturals, for example, 1260 + ... + 12821.

It is an arithmetic number, because the mean of its divisors is an integer number (7097328).

Almost surely, 2^81402261 is an apocalyptic number.

It is an amenable number.

81402261 is a deficient number, since it is larger than the sum of its proper divisors (32154987).

81402261 is a wasteful number, since it uses less digits than its factorization.

81402261 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 14172.

The product of its (nonzero) digits is 768, while the sum is 24.

The square root of 81402261 is about 9022.3201561461. The cubic root of 81402261 is about 433.3899365245.

Adding to 81402261 its reverse (16220418), we get a palindrome (97622679).

It can be divided in two parts, 8140 and 2261, that added together give a palindrome (10401).

The spelling of 81402261 in words is "eighty-one million, four hundred two thousand, two hundred sixty-one".