81010101 has 4 divisors (see below), whose sum is σ = 108013472. Its totient is φ = 54006732.

The previous prime is 81010087. The next prime is 81010103. The reversal of 81010101 is 10101018.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is not a de Polignac number, because 81010101 - 2⁹ = 81009589 is a prime.

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

It is a Duffinian number.

81010101 is a modest number, since divided by 10101 gives 81 as remainder.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81010103) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 13501681 + ... + 13501686.

It is an arithmetic number, because the mean of its divisors is an integer number (27003368).

Almost surely, 2^81010101 is an apocalyptic number.

It is an amenable number.

81010101 is a deficient number, since it is larger than the sum of its proper divisors (27003371).

81010101 is a wasteful number, since it uses less digits than its factorization.

81010101 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 27003370.

The product of its (nonzero) digits is 8, while the sum is 12.

The square root of 81010101 is about 9000.5611491729. The cubic root of 81010101 is about 432.6928557310.

Adding to 81010101 its reverse (10101018), we get a palindrome (91111119).

It can be divided in two parts, 8 and 1010101, that multiplied together give a palindrome (8080808).

The spelling of 81010101 in words is "eighty-one million, ten thousand, one hundred one".