21542150321 has 4 divisors (see below), whose sum is σ = 22809335652. Its totient is φ = 20274964992.

The previous prime is 21542150099. The next prime is 21542150381. The reversal of 21542150321 is 12305124512.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 11363560000 + 10178590321 = 106600^2 + 100889^2 .

It is a cyclic number.

It is not a de Polignac number, because 21542150321 - 2²⁶ = 21475041457 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21542150381) 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, 633592640 + ... + 633592673.

It is an arithmetic number, because the mean of its divisors is an integer number (5702333913).

Almost surely, 2^21542150321 is an apocalyptic number.

It is an amenable number.

21542150321 is a deficient number, since it is larger than the sum of its proper divisors (1267185331).

21542150321 is a wasteful number, since it uses less digits than its factorization.

21542150321 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1267185330.

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

Adding to 21542150321 its reverse (12305124512), we get a palindrome (33847274833).

The spelling of 21542150321 in words is "twenty-one billion, five hundred forty-two million, one hundred fifty thousand, three hundred twenty-one".