81187019 has 8 divisors (see below), whose sum is σ = 90487440. Its totient is φ = 72389376.

The previous prime is 81187013. The next prime is 81187021. The reversal of 81187019 is 91078118.

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

It is a cyclic number.

It is not a de Polignac number, because 81187019 - 2¹² = 81182923 is a prime.

It is a super-2 number, since 2×81187019² = 13182664108212722, which contains 22 as substring.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 81187019.

It is not an unprimeable number, because it can be changed into a prime (81187013) 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, 125354 + ... + 125999.

It is an arithmetic number, because the mean of its divisors is an integer number (11310930).

Almost surely, 2^81187019 is an apocalyptic number.

81187019 is a deficient number, since it is larger than the sum of its proper divisors (9300421).

81187019 is a wasteful number, since it uses less digits than its factorization.

81187019 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 251389.

The product of its (nonzero) digits is 4032, while the sum is 35.

The square root of 81187019 is about 9010.3839540832. The cubic root of 81187019 is about 433.0076127572.

The spelling of 81187019 in words is "eighty-one million, one hundred eighty-seven thousand, nineteen".