81356004 has 18 divisors (see below), whose sum is σ = 205649990. Its totient is φ = 27118656.

The previous prime is 81355979. The next prime is 81356021. The reversal of 81356004 is 40065318.

It can be written as a sum of positive squares in only one way, i.e., 54730404 + 26625600 = 7398^2 + 5160^2 .

It is a tau number, because it is divible by the number of its divisors (18).

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 1129909 + ... + 1129980.

Almost surely, 2^81356004 is an apocalyptic number.

It is an amenable number.

81356004 is an abundant number, since it is smaller than the sum of its proper divisors (124293986).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

81356004 is a wasteful number, since it uses less digits than its factorization.

81356004 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2259899 (or 2259894 counting only the distinct ones).

The product of its (nonzero) digits is 2880, while the sum is 27.

The square root of 81356004 is about 9019.7563159988. The cubic root of 81356004 is about 433.3078293997.

The spelling of 81356004 in words is "eighty-one million, three hundred fifty-six thousand, four".