21742423154 has 4 divisors (see below), whose sum is σ = 32613634734. Its totient is φ = 10871211576.

The previous prime is 21742423151. The next prime is 21742423163. The reversal of 21742423154 is 45132424712.

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

It can be written as a sum of positive squares in only one way, i.e., 16660871929 + 5081551225 = 129077^2 + 71285^2 .

It is not an unprimeable number, because it can be changed into a prime (21742423151) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5435605787 + ... + 5435605790.

Almost surely, 2^21742423154 is an apocalyptic number.

21742423154 is a deficient number, since it is larger than the sum of its proper divisors (10871211580).

21742423154 is a wasteful number, since it uses less digits than its factorization.

21742423154 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10871211579.

The product of its digits is 53760, while the sum is 35.

Adding to 21742423154 its reverse (45132424712), we get a palindrome (66874847866).

The spelling of 21742423154 in words is "twenty-one billion, seven hundred forty-two million, four hundred twenty-three thousand, one hundred fifty-four".