81894641 has 2 divisors, whose sum is σ = 81894642. Its totient is φ = 81894640.

The previous prime is 81894611. The next prime is 81894647. The reversal of 81894641 is 14649818.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 79584241 + 2310400 = 8921^2 + 1520^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-81894641 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (81894647) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40947320 + 40947321.

It is an arithmetic number, because the mean of its divisors is an integer number (40947321).

Almost surely, 2^81894641 is an apocalyptic number.

It is an amenable number.

81894641 is a deficient number, since it is larger than the sum of its proper divisors (1).

81894641 is an equidigital number, since it uses as much as digits as its factorization.

81894641 is an evil number, because the sum of its binary digits is even.

The product of its digits is 55296, while the sum is 41.

The square root of 81894641 is about 9049.5657906885. The cubic root of 81894641 is about 434.2619996315.

It can be divided in two parts, 818 and 94641, that added together give a palindrome (95459).

The spelling of 81894641 in words is "eighty-one million, eight hundred ninety-four thousand, six hundred forty-one".