72021221161 has 4 divisors (see below), whose sum is σ = 72022545792. Its totient is φ = 72019896532.

The previous prime is 72021221159. The next prime is 72021221219. The reversal of 72021221161 is 16112212027.

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, and also an emirpimes, since its reverse is a distinct semiprime: 16112212027 = 1091 ⋅14768297.

It is a cyclic number.

It is not a de Polignac number, because 72021221161 - 2¹ = 72021221159 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (72021221101) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 577105 + ... + 690718.

It is an arithmetic number, because the mean of its divisors is an integer number (18005636448).

Almost surely, 2^72021221161 is an apocalyptic number.

It is an amenable number.

72021221161 is a deficient number, since it is larger than the sum of its proper divisors (1324631).

72021221161 is a wasteful number, since it uses less digits than its factorization.

72021221161 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1324630.

The product of its (nonzero) digits is 672, while the sum is 25.

Adding to 72021221161 its reverse (16112212027), we get a palindrome (88133433188).

The spelling of 72021221161 in words is "seventy-two billion, twenty-one million, two hundred twenty-one thousand, one hundred sixty-one".