81921101 has 8 divisors (see below), whose sum is σ = 86760384. Its totient is φ = 77188320.

The previous prime is 81921097. The next prime is 81921107. The reversal of 81921101 is 10112918.

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 81921101 - 2² = 81921097 is a prime.

It is a super-3 number, since 3×81921101³ (a number of 25 digits) contains 333 as substring. Note that it is a super-d number also for d = 2.

It is a Harshad number since it is a multiple of its sum of digits (23).

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81921107) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 25040 + ... + 28121.

It is an arithmetic number, because the mean of its divisors is an integer number (10845048).

Almost surely, 2^81921101 is an apocalyptic number.

It is an amenable number.

81921101 is a deficient number, since it is larger than the sum of its proper divisors (4839283).

81921101 is a wasteful number, since it uses less digits than its factorization.

81921101 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 53251.

The product of its (nonzero) digits is 144, while the sum is 23.

The square root of 81921101 is about 9051.0276212152. The cubic root of 81921101 is about 434.3087643325.

The spelling of 81921101 in words is "eighty-one million, nine hundred twenty-one thousand, one hundred one".