81929481 has 4 divisors (see below), whose sum is σ = 109239312. Its totient is φ = 54619652.

The previous prime is 81929461. The next prime is 81929489. The reversal of 81929481 is 18492918.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 81929481 - 2¹³ = 81921289 is a prime.

It is a super-2 number, since 2×81929481² = 13424879713858722, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (81929489) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 13654911 + ... + 13654916.

It is an arithmetic number, because the mean of its divisors is an integer number (27309828).

Almost surely, 2^81929481 is an apocalyptic number.

It is an amenable number.

81929481 is a deficient number, since it is larger than the sum of its proper divisors (27309831).

81929481 is a wasteful number, since it uses less digits than its factorization.

81929481 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 27309830.

The product of its digits is 41472, while the sum is 42.

The square root of 81929481 is about 9051.4905402370. The cubic root of 81929481 is about 434.3235728223.

The spelling of 81929481 in words is "eighty-one million, nine hundred twenty-nine thousand, four hundred eighty-one".