72106621 has 4 divisors (see below), whose sum is σ = 72175644. Its totient is φ = 72037600.

The previous prime is 72106609. The next prime is 72106631. The reversal of 72106621 is 12660127.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 12660127 = 1867 ⋅6781.

It can be written as a sum of positive squares in 2 ways, for example, as 61936900 + 10169721 = 7870^2 + 3189^2 .

It is a cyclic number.

It is not a de Polignac number, because 72106621 - 2¹⁷ = 71975549 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 (72106631) 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, 32920 + ... + 35041.

It is an arithmetic number, because the mean of its divisors is an integer number (18043911).

Almost surely, 2^72106621 is an apocalyptic number.

It is an amenable number.

72106621 is a deficient number, since it is larger than the sum of its proper divisors (69023).

72106621 is a wasteful number, since it uses less digits than its factorization.

72106621 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 69022.

The product of its (nonzero) digits is 1008, while the sum is 25.

The square root of 72106621 is about 8491.5617527049. The cubic root of 72106621 is about 416.2220157519. Note that the first 3 decimals are identical.

Adding to 72106621 its reverse (12660127), we get a palindrome (84766748).

It can be divided in two parts, 72106 and 621, that added together give a palindrome (72727).

The spelling of 72106621 in words is "seventy-two million, one hundred six thousand, six hundred twenty-one".