81620575 has 6 divisors (see below), whose sum is σ = 101209544. Its totient is φ = 65296440.

The previous prime is 81620569. The next prime is 81620597. The reversal of 81620575 is 57502618.

It is not a de Polignac number, because 81620575 - 2¹¹ = 81618527 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 81620575.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 1632387 + ... + 1632436.

Almost surely, 2^81620575 is an apocalyptic number.

81620575 is a deficient number, since it is larger than the sum of its proper divisors (19588969).

81620575 is a wasteful number, since it uses less digits than its factorization.

81620575 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3264833 (or 3264828 counting only the distinct ones).

The product of its (nonzero) digits is 16800, while the sum is 34.

The square root of 81620575 is about 9034.4106061215. The cubic root of 81620575 is about 433.7770291024. Note that the first 3 decimals are identical.

The spelling of 81620575 in words is "eighty-one million, six hundred twenty thousand, five hundred seventy-five".