81534553 has 2 divisors, whose sum is σ = 81534554. Its totient is φ = 81534552.

The previous prime is 81534487. The next prime is 81534641. The reversal of 81534553 is 35543518.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 70425664 + 11108889 = 8392^2 + 3333^2 .

It is a cyclic number.

It is not a de Polignac number, because 81534553 - 2⁹ = 81534041 is a prime.

It is not a weakly prime, because it can be changed into another prime (81534253) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40767276 + 40767277.

It is an arithmetic number, because the mean of its divisors is an integer number (40767277).

Almost surely, 2^81534553 is an apocalyptic number.

It is an amenable number.

81534553 is a deficient number, since it is larger than the sum of its proper divisors (1).

81534553 is an equidigital number, since it uses as much as digits as its factorization.

81534553 is an evil number, because the sum of its binary digits is even.

The product of its digits is 36000, while the sum is 34.

The square root of 81534553 is about 9029.6485535152. The cubic root of 81534553 is about 433.6245859873.

The spelling of 81534553 in words is "eighty-one million, five hundred thirty-four thousand, five hundred fifty-three".