81284969 has 4 divisors (see below), whose sum is σ = 81306180. Its totient is φ = 81263760.

The previous prime is 81284963. The next prime is 81284981. The reversal of 81284969 is 96948218.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 58369600 + 22915369 = 7640^2 + 4787^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-81284969 is a prime.

It is a super-2 number, since 2×81284969² = 13214492370661922, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81284963) 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, 3074 + ... + 13115.

It is an arithmetic number, because the mean of its divisors is an integer number (20326545).

Almost surely, 2^81284969 is an apocalyptic number.

It is an amenable number.

81284969 is a deficient number, since it is larger than the sum of its proper divisors (21211).

81284969 is a wasteful number, since it uses less digits than its factorization.

81284969 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 21210.

The product of its digits is 248832, while the sum is 47.

The square root of 81284969 is about 9015.8177111120. The cubic root of 81284969 is about 433.1816801999.

The spelling of 81284969 in words is "eighty-one million, two hundred eighty-four thousand, nine hundred sixty-nine".