20150511221 has 4 divisors (see below), whose sum is σ = 20800527744. Its totient is φ = 19500494700.

The previous prime is 20150511211. The next prime is 20150511253. The reversal of 20150511221 is 12211505102.

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: 12211505102 = 2 ⋅6105752551.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20150511221 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 20150511193 and 20150511202.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20150511211) 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, 325008215 + ... + 325008276.

It is an arithmetic number, because the mean of its divisors is an integer number (5200131936).

Almost surely, 2^20150511221 is an apocalyptic number.

It is an amenable number.

20150511221 is a deficient number, since it is larger than the sum of its proper divisors (650016523).

20150511221 is an equidigital number, since it uses as much as digits as its factorization.

20150511221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 650016522.

The product of its (nonzero) digits is 200, while the sum is 20.

The spelling of 20150511221 in words is "twenty billion, one hundred fifty million, five hundred eleven thousand, two hundred twenty-one".