81378441 has 27 divisors (see below), whose sum is σ = 122725863. Its totient is φ = 51960960.

The previous prime is 81378433. The next prime is 81378449. The reversal of 81378441 is 14487318.

The square root of 81378441 is 9021.

It is a perfect power (a square), and thus also a powerful number.

It is an interprime number because it is at equal distance from previous prime (81378433) and next prime (81378449).

It can be written as a sum of positive squares in only one way, i.e., 36542025 + 44836416 = 6045^2 + 6696^2 .

It is not a de Polignac number, because 81378441 - 2³ = 81378433 is a prime.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 81378396 and 81378405.

It is not an unprimeable number, because it can be changed into a prime (81378449) by changing a digit.

It is a polite number, since it can be written in 26 ways as a sum of consecutive naturals, for example, 838905 + ... + 839001.

Almost surely, 2^81378441 is an apocalyptic number.

81378441 is the 9021-st square number.

81378441 is the 4511-st centered octagonal number.

It is an amenable number.

81378441 is a deficient number, since it is larger than the sum of its proper divisors (41347422).

81378441 is an equidigital number, since it uses as much as digits as its factorization.

81378441 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 262 (or 131 counting only the distinct ones).

The product of its digits is 21504, while the sum is 36.

The cubic root of 81378441 is about 433.3476594212.

Multiplying 81378441 by its sum of digits (36), we get a square (2929623876 = 54126²).

The spelling of 81378441 in words is "eighty-one million, three hundred seventy-eight thousand, four hundred forty-one".