72002171821 has 8 divisors (see below), whose sum is σ = 72073330560. Its totient is φ = 71931044928.

The previous prime is 72002171809. The next prime is 72002171881. The reversal of 72002171821 is 12817120027.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-72002171821 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 (72002171881) 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, 8282245 + ... + 8290933.

It is an arithmetic number, because the mean of its divisors is an integer number (9009166320).

Almost surely, 2^72002171821 is an apocalyptic number.

It is an amenable number.

72002171821 is a deficient number, since it is larger than the sum of its proper divisors (71158739).

72002171821 is a wasteful number, since it uses less digits than its factorization.

72002171821 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 15923.

The product of its (nonzero) digits is 3136, while the sum is 31.

Adding to 72002171821 its reverse (12817120027), we get a palindrome (84819291848).

The spelling of 72002171821 in words is "seventy-two billion, two million, one hundred seventy-one thousand, eight hundred twenty-one".