81214381 has 2 divisors, whose sum is σ = 81214382. Its totient is φ = 81214380.

The previous prime is 81214337. The next prime is 81214411. The reversal of 81214381 is 18341218.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 51337225 + 29877156 = 7165^2 + 5466^2 .

It is a cyclic number.

It is not a de Polignac number, because 81214381 - 2²⁵ = 47659949 is a prime.

It is a super-2 number, since 2×81214381² = 13191551362426322, which contains 22 as substring.

It is a Chen prime.

It is an alternating number because its digits alternate between even and odd.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81214981) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40607190 + 40607191.

It is an arithmetic number, because the mean of its divisors is an integer number (40607191).

Almost surely, 2^81214381 is an apocalyptic number.

It is an amenable number.

81214381 is a deficient number, since it is larger than the sum of its proper divisors (1).

81214381 is an equidigital number, since it uses as much as digits as its factorization.

81214381 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1536, while the sum is 28.

The square root of 81214381 is about 9011.9021854434. The cubic root of 81214381 is about 433.0562519924.

Adding to 81214381 its reverse (18341218), we get a palindrome (99555599).

The spelling of 81214381 in words is "eighty-one million, two hundred fourteen thousand, three hundred eighty-one".