71839981 has 8 divisors (see below), whose sum is σ = 72396864. Its totient is φ = 71285760.

The previous prime is 71839979. The next prime is 71839991. The reversal of 71839981 is 18993817.

71839981 = T₆₉₁₉ + T₆₉₂₀ + T₆₉₂₁.

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 71839981 - 2¹ = 71839979 is a prime.

It is a super-2 number, since 2×71839981² = 10321965740160722, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (71839921) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 113536 + ... + 114166.

It is an arithmetic number, because the mean of its divisors is an integer number (9049608).

Almost surely, 2^71839981 is an apocalyptic number.

71839981 is the 6921-st centered triangular number.

It is an amenable number.

71839981 is a deficient number, since it is larger than the sum of its proper divisors (556883).

71839981 is a wasteful number, since it uses less digits than its factorization.

71839981 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1331.

The product of its digits is 108864, while the sum is 46.

The square root of 71839981 is about 8475.8469193350. The cubic root of 71839981 is about 415.7083388463.

The spelling of 71839981 in words is "seventy-one million, eight hundred thirty-nine thousand, nine hundred eighty-one".