81294989 has 4 divisors (see below), whose sum is σ = 83917440. Its totient is φ = 78672540.

The previous prime is 81294973. The next prime is 81294991. The reversal of 81294989 is 98949218.

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 a cyclic number.

It is not a de Polignac number, because 81294989 - 2⁴ = 81294973 is a prime.

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

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81294959) 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, 1311179 + ... + 1311240.

It is an arithmetic number, because the mean of its divisors is an integer number (20979360).

Almost surely, 2^81294989 is an apocalyptic number.

It is an amenable number.

81294989 is a deficient number, since it is larger than the sum of its proper divisors (2622451).

81294989 is a wasteful number, since it uses less digits than its factorization.

81294989 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2622450.

The product of its digits is 373248, while the sum is 50.

The square root of 81294989 is about 9016.3733840164. The cubic root of 81294989 is about 433.1994789072.

The spelling of 81294989 in words is "eighty-one million, two hundred ninety-four thousand, nine hundred eighty-nine".