81419521 has 2 divisors, whose sum is σ = 81419522. Its totient is φ = 81419520.

The previous prime is 81419519. The next prime is 81419531. The reversal of 81419521 is 12591418.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 62583921 + 18835600 = 7911^2 + 4340^2 .

It is a cyclic number.

It is not a de Polignac number, because 81419521 - 2¹ = 81419519 is a prime.

Together with 81419519, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (81419531) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40709760 + 40709761.

It is an arithmetic number, because the mean of its divisors is an integer number (40709761).

Almost surely, 2^81419521 is an apocalyptic number.

It is an amenable number.

81419521 is a deficient number, since it is larger than the sum of its proper divisors (1).

81419521 is an equidigital number, since it uses as much as digits as its factorization.

81419521 is an evil number, because the sum of its binary digits is even.

The product of its digits is 2880, while the sum is 31.

The square root of 81419521 is about 9023.2766221589. The cubic root of 81419521 is about 433.4205654103.

The spelling of 81419521 in words is "eighty-one million, four hundred nineteen thousand, five hundred twenty-one".