81698817 has 4 divisors (see below), whose sum is σ = 108931760. Its totient is φ = 54465876.

The previous prime is 81698807. The next prime is 81698863. The reversal of 81698817 is 71889618.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is not a de Polignac number, because 81698817 - 2¹² = 81694721 is a prime.

It is a super-4 number, since 4×81698817⁴ (a number of 33 digits) contains 4444 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81698807) 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, 13616467 + ... + 13616472.

It is an arithmetic number, because the mean of its divisors is an integer number (27232940).

Almost surely, 2^81698817 is an apocalyptic number.

It is an amenable number.

81698817 is a deficient number, since it is larger than the sum of its proper divisors (27232943).

81698817 is a wasteful number, since it uses less digits than its factorization.

81698817 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 27232942.

The product of its digits is 193536, while the sum is 48.

The square root of 81698817 is about 9038.7397904796. The cubic root of 81698817 is about 433.9155919716.

The spelling of 81698817 in words is "eighty-one million, six hundred ninety-eight thousand, eight hundred seventeen".