81705490 has 8 divisors (see below), whose sum is σ = 147069900. Its totient is φ = 32682192.

The previous prime is 81705487. The next prime is 81705511. The reversal of 81705490 is 9450718.

It is a happy number.

It can be written as a sum of positive squares in 2 ways, for example, as 75012921 + 6692569 = 8661^2 + 2587^2 .

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

It is a super-2 number, since 2×81705490² = 13351574192280200, which contains 22 as substring.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 4085265 + ... + 4085284.

Almost surely, 2^81705490 is an apocalyptic number.

81705490 is a deficient number, since it is larger than the sum of its proper divisors (65364410).

81705490 is a wasteful number, since it uses less digits than its factorization.

81705490 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8170556.

The product of its (nonzero) digits is 10080, while the sum is 34.

The square root of 81705490 is about 9039.1089162594. The cubic root of 81705490 is about 433.9274054430.

The spelling of 81705490 in words is "eighty-one million, seven hundred five thousand, four hundred ninety".