81212261 has 8 divisors (see below), whose sum is σ = 88942560. Its totient is φ = 73693872.

The previous prime is 81212249. The next prime is 81212273. The reversal of 81212261 is 16221218.

It is an interprime number because it is at equal distance from previous prime (81212249) and next prime (81212273).

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 81212261 - 2¹⁰ = 81211237 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 (81212221) 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, 52175 + ... + 53708.

It is an arithmetic number, because the mean of its divisors is an integer number (11117820).

Almost surely, 2^81212261 is an apocalyptic number.

It is an amenable number.

81212261 is a deficient number, since it is larger than the sum of its proper divisors (7730299).

81212261 is a wasteful number, since it uses less digits than its factorization.

81212261 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 105955.

The product of its digits is 384, while the sum is 23.

The square root of 81212261 is about 9011.7845624493. The cubic root of 81212261 is about 433.0524838287.

Adding to 81212261 its reverse (16221218), we get a palindrome (97433479).

The spelling of 81212261 in words is "eighty-one million, two hundred twelve thousand, two hundred sixty-one".