81378001 has 4 divisors (see below), whose sum is σ = 81399604. Its totient is φ = 81356400.

The previous prime is 81377993. The next prime is 81378013. The reversal of 81378001 is 10087318.

It is a happy number.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 77457601 + 3920400 = 8801^2 + 1980^2 .

It is a cyclic number.

It is not a de Polignac number, because 81378001 - 2³ = 81377993 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81378091) 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, 3510 + ... + 13231.

It is an arithmetic number, because the mean of its divisors is an integer number (20349901).

Almost surely, 2^81378001 is an apocalyptic number.

It is an amenable number.

81378001 is a deficient number, since it is larger than the sum of its proper divisors (21603).

81378001 is a wasteful number, since it uses less digits than its factorization.

81378001 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 21602.

The product of its (nonzero) digits is 1344, while the sum is 28.

The square root of 81378001 is about 9020.9756124269. The cubic root of 81378001 is about 433.3468784063.

The spelling of 81378001 in words is "eighty-one million, three hundred seventy-eight thousand, one".