81534641 has 2 divisors, whose sum is σ = 81534642. Its totient is φ = 81534640.

The previous prime is 81534553. The next prime is 81534647. The reversal of 81534641 is 14643518.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 79834225 + 1700416 = 8935^2 + 1304^2 .

It is a cyclic number.

It is not a de Polignac number, because 81534641 - 2²⁶ = 14425777 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 81534598 and 81534607.

It is not a weakly prime, because it can be changed into another prime (81534647) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40767320 + 40767321.

It is an arithmetic number, because the mean of its divisors is an integer number (40767321).

Almost surely, 2^81534641 is an apocalyptic number.

It is an amenable number.

81534641 is a deficient number, since it is larger than the sum of its proper divisors (1).

81534641 is an equidigital number, since it uses as much as digits as its factorization.

81534641 is an evil number, because the sum of its binary digits is even.

The product of its digits is 11520, while the sum is 32.

The square root of 81534641 is about 9029.6534263503. The cubic root of 81534641 is about 433.6247419905.

The spelling of 81534641 in words is "eighty-one million, five hundred thirty-four thousand, six hundred forty-one".