81871442 has 4 divisors (see below), whose sum is σ = 122807166. Its totient is φ = 40935720.

The previous prime is 81871423. The next prime is 81871457. The reversal of 81871442 is 24417818.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 24417818 = 2 ⋅12208909.

It can be written as a sum of positive squares in only one way, i.e., 81558961 + 312481 = 9031^2 + 559^2 .

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 20467859 + ... + 20467862.

Almost surely, 2^81871442 is an apocalyptic number.

81871442 is a deficient number, since it is larger than the sum of its proper divisors (40935724).

81871442 is a wasteful number, since it uses less digits than its factorization.

81871442 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 40935723.

The product of its digits is 14336, while the sum is 35.

The square root of 81871442 is about 9048.2839256955. The cubic root of 81871442 is about 434.2209900471.

The spelling of 81871442 in words is "eighty-one million, eight hundred seventy-one thousand, four hundred forty-two".