81437885 has 8 divisors (see below), whose sum is σ = 98060760. Its totient is φ = 64926784.

The previous prime is 81437843. The next prime is 81437891. The reversal of 81437885 is 58873418.

It can be written as a sum of positive squares in 4 ways, for example, as 5207524 + 76230361 = 2282^2 + 8731^2 .

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 81437885 - 2⁶ = 81437821 is a prime.

It is a super-2 number, since 2×81437885² = 13264258226546450, which contains 22 as substring.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 26330 + ... + 29259.

It is an arithmetic number, because the mean of its divisors is an integer number (12257595).

Almost surely, 2^81437885 is an apocalyptic number.

It is an amenable number.

81437885 is a deficient number, since it is larger than the sum of its proper divisors (16622875).

81437885 is a wasteful number, since it uses less digits than its factorization.

81437885 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 55887.

The product of its digits is 215040, while the sum is 44.

The square root of 81437885 is about 9024.2941552234. The cubic root of 81437885 is about 433.4531486567.

The spelling of 81437885 in words is "eighty-one million, four hundred thirty-seven thousand, eight hundred eighty-five".