81640154 has 8 divisors (see below), whose sum is σ = 129663828. Its totient is φ = 38418880.

The previous prime is 81640151. The next prime is 81640159. The reversal of 81640154 is 45104618.

It can be written as a sum of positive squares in 2 ways, for example, as 81414529 + 225625 = 9023^2 + 475^2 .

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

It is a super-2 number, since 2×81640154² = 13330229490287432, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (81640151) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1200557 + ... + 1200624.

Almost surely, 2^81640154 is an apocalyptic number.

81640154 is a deficient number, since it is larger than the sum of its proper divisors (48023674).

81640154 is a wasteful number, since it uses less digits than its factorization.

81640154 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2401200.

The product of its (nonzero) digits is 3840, while the sum is 29.

The square root of 81640154 is about 9035.4941204120. The cubic root of 81640154 is about 433.8117108864.

The spelling of 81640154 in words is "eighty-one million, six hundred forty thousand, one hundred fifty-four".