81221489 has 8 divisors (see below), whose sum is σ = 84969000. Its totient is φ = 77537152.

The previous prime is 81221471. The next prime is 81221507. The reversal of 81221489 is 98412218.

It is an interprime number because it is at equal distance from previous prime (81221471) and next prime (81221507).

It can be written as a sum of positive squares in 4 ways, for example, as 4080400 + 77141089 = 2020^2 + 8783^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 81221489 - 2⁸ = 81221233 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81223489) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 13154 + ... + 18315.

It is an arithmetic number, because the mean of its divisors is an integer number (10621125).

Almost surely, 2^81221489 is an apocalyptic number.

81221489 is a gapful number since it is divisible by the number (89) formed by its first and last digit.

It is an amenable number.

81221489 is a deficient number, since it is larger than the sum of its proper divisors (3747511).

81221489 is a wasteful number, since it uses less digits than its factorization.

81221489 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 31587.

The product of its digits is 9216, while the sum is 35.

The square root of 81221489 is about 9012.2965441668. The cubic root of 81221489 is about 433.0688855269.

The spelling of 81221489 in words is "eighty-one million, two hundred twenty-one thousand, four hundred eighty-nine".