20154531221 has 4 divisors (see below), whose sum is σ = 21986761344. Its totient is φ = 18322301100.

The previous prime is 20154531209. The next prime is 20154531259. The reversal of 20154531221 is 12213545102.

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 a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20154531221 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 (20154531121) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 916115045 + ... + 916115066.

It is an arithmetic number, because the mean of its divisors is an integer number (5496690336).

Almost surely, 2^20154531221 is an apocalyptic number.

It is an amenable number.

20154531221 is a deficient number, since it is larger than the sum of its proper divisors (1832230123).

20154531221 is a wasteful number, since it uses less digits than its factorization.

20154531221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1832230122.

The product of its (nonzero) digits is 2400, while the sum is 26.

The spelling of 20154531221 in words is "twenty billion, one hundred fifty-four million, five hundred thirty-one thousand, two hundred twenty-one".