81122621 has 4 divisors (see below), whose sum is σ = 81576000. Its totient is φ = 80669244.

The previous prime is 81122557. The next prime is 81122627. The reversal of 81122621 is 12622118.

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 81122621 - 2⁶ = 81122557 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 (81122627) 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, 226421 + ... + 226778.

It is an arithmetic number, because the mean of its divisors is an integer number (20394000).

Almost surely, 2^81122621 is an apocalyptic number.

It is an amenable number.

81122621 is a deficient number, since it is larger than the sum of its proper divisors (453379).

81122621 is a wasteful number, since it uses less digits than its factorization.

81122621 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 453378.

The product of its digits is 384, while the sum is 23.

The square root of 81122621 is about 9006.8097015536. The cubic root of 81122621 is about 432.8930944486.

Adding to 81122621 its reverse (12622118), we get a palindrome (93744739).

It can be divided in two parts, 811 and 22621, that added together give a palindrome (23432).

The spelling of 81122621 in words is "eighty-one million, one hundred twenty-two thousand, six hundred twenty-one".