81429885 has 12 divisors (see below), whose sum is σ = 141145212. Its totient is φ = 43429248.

The previous prime is 81429827. The next prime is 81429893. The reversal of 81429885 is 58892418.

It is a happy number.

It can be written as a sum of positive squares in 2 ways, for example, as 48734361 + 32695524 = 6981^2 + 5718^2 .

It is not a de Polignac number, because 81429885 - 2⁷ = 81429757 is a prime.

It is a super-2 number, since 2×81429885² = 13261652342226450, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (45), and also a Moran number because the ratio is a prime number: 1809553 = 81429885 / (8 + 1 + 4 + 2 + 9 + 8 + 8 + 5).

It is a self number, because there is not a number n which added to its sum of digits gives 81429885.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 904732 + ... + 904821.

It is an arithmetic number, because the mean of its divisors is an integer number (11762101).

Almost surely, 2^81429885 is an apocalyptic number.

It is an amenable number.

81429885 is a deficient number, since it is larger than the sum of its proper divisors (59715327).

81429885 is a wasteful number, since it uses less digits than its factorization.

81429885 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1809564 (or 1809561 counting only the distinct ones).

The product of its digits is 184320, while the sum is 45.

The square root of 81429885 is about 9023.8508963746. The cubic root of 81429885 is about 433.4389548584.

The spelling of 81429885 in words is "eighty-one million, four hundred twenty-nine thousand, eight hundred eighty-five".