81698945 has 12 divisors (see below), whose sum is σ = 101541180. Its totient is φ = 63102144.

The previous prime is 81698941. The next prime is 81698951. The reversal of 81698945 is 54989618.

It is a happy number.

It can be written as a sum of positive squares in 6 ways, for example, as 12609601 + 69089344 = 3551^2 + 8312^2 .

It is not a de Polignac number, because 81698945 - 2² = 81698941 is a prime.

It is a super-2 number, since 2×81698945² = 13349435228226050, which contains 22 as substring.

It is an alternating number because its digits alternate between even and odd.

It is a junction number, because it is equal to n+sod(n) for n = 81698893 and 81698902.

It is not an unprimeable number, because it can be changed into a prime (81698941) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 5510 + ... + 13919.

It is an arithmetic number, because the mean of its divisors is an integer number (8461765).

Almost surely, 2^81698945 is an apocalyptic number.

It is an amenable number.

81698945 is a deficient number, since it is larger than the sum of its proper divisors (19842235).

81698945 is a wasteful number, since it uses less digits than its factorization.

81698945 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 19492 (or 19463 counting only the distinct ones).

The product of its digits is 622080, while the sum is 50.

The square root of 81698945 is about 9038.7468711100. The cubic root of 81698945 is about 433.9158185811.

The spelling of 81698945 in words is "eighty-one million, six hundred ninety-eight thousand, nine hundred forty-five".