81217090 has 8 divisors (see below), whose sum is σ = 146190780. Its totient is φ = 32486832.

The previous prime is 81217079. The next prime is 81217091. The reversal of 81217090 is 9071218.

It can be written as a sum of positive squares in 2 ways, for example, as 80335369 + 881721 = 8963^2 + 939^2 .

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

It is not an unprimeable number, because it can be changed into a prime (81217091) 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, 4060845 + ... + 4060864.

Almost surely, 2^81217090 is an apocalyptic number.

81217090 is a deficient number, since it is larger than the sum of its proper divisors (64973690).

81217090 is a wasteful number, since it uses less digits than its factorization.

81217090 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8121716.

The product of its (nonzero) digits is 1008, while the sum is 28.

The square root of 81217090 is about 9012.0524854220. The cubic root of 81217090 is about 433.0610669703.

The spelling of 81217090 in words is "eighty-one million, two hundred seventeen thousand, ninety".