81378285861 has 8 divisors (see below), whose sum is σ = 108727184704. Its totient is φ = 54140788800.

The previous prime is 81378285853. The next prime is 81378285869. The reversal of 81378285861 is 16858287318.

It is an interprime number because it is at equal distance from previous prime (81378285853) and next prime (81378285869).

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

It is not a de Polignac number, because 81378285861 - 2³ = 81378285853 is a prime.

It is a super-2 number, since 2×81378285861² (a number of 23 digits) contains 22 as substring.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81378285869) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 27848740 + ... + 27851661.

It is an arithmetic number, because the mean of its divisors is an integer number (13590898088).

Almost surely, 2^81378285861 is an apocalyptic number.

It is an amenable number.

81378285861 is a deficient number, since it is larger than the sum of its proper divisors (27348898843).

81378285861 is a wasteful number, since it uses less digits than its factorization.

81378285861 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 55700891.

The product of its digits is 5160960, while the sum is 57.

The spelling of 81378285861 in words is "eighty-one billion, three hundred seventy-eight million, two hundred eighty-five thousand, eight hundred sixty-one".