81142237 has 6 divisors (see below), whose sum is σ = 89189534. Its totient is φ = 73765560.

The previous prime is 81142219. The next prime is 81142253. The reversal of 81142237 is 73224118.

It can be written as a sum of positive squares in only one way, i.e., 61685316 + 19456921 = 7854^2 + 4411^2 .

It is not a de Polignac number, because 81142237 - 2⁷ = 81142109 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81142637) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 335178 + ... + 335419.

Almost surely, 2^81142237 is an apocalyptic number.

It is an amenable number.

81142237 is a deficient number, since it is larger than the sum of its proper divisors (8047297).

81142237 is a wasteful number, since it uses less digits than its factorization.

81142237 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 670619 (or 670608 counting only the distinct ones).

The product of its digits is 2688, while the sum is 28.

The square root of 81142237 is about 9007.8985895713. The cubic root of 81142237 is about 432.9279837987.

The spelling of 81142237 in words is "eighty-one million, one hundred forty-two thousand, two hundred thirty-seven".