16215552021 has 4 divisors (see below), whose sum is σ = 21620736032. Its totient is φ = 10810368012.

The previous prime is 16215551999. The next prime is 16215552049. The reversal of 16215552021 is 12025551261.

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 not a de Polignac number, because 16215552021 - 2¹⁵ = 16215519253 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 16215552021.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (16215552091) 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, 2702592001 + ... + 2702592006.

It is an arithmetic number, because the mean of its divisors is an integer number (5405184008).

Almost surely, 2^16215552021 is an apocalyptic number.

It is an amenable number.

16215552021 is a deficient number, since it is larger than the sum of its proper divisors (5405184011).

16215552021 is an equidigital number, since it uses as much as digits as its factorization.

16215552021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5405184010.

The product of its (nonzero) digits is 6000, while the sum is 30.

The spelling of 16215552021 in words is "sixteen billion, two hundred fifteen million, five hundred fifty-two thousand, twenty-one".