21542309887 has 24 divisors (see below), whose sum is σ = 25777055360. Its totient is φ = 17634363120.

The previous prime is 21542309879. The next prime is 21542309891. The reversal of 21542309887 is 78890324512.

It is not a de Polignac number, because 21542309887 - 2³ = 21542309879 is a prime.

It is a super-2 number, since 2×21542309887² (a number of 21 digits) contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 21542309887.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21542309827) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 2554564 + ... + 2562982.

Almost surely, 2^21542309887 is an apocalyptic number.

21542309887 is a deficient number, since it is larger than the sum of its proper divisors (4234745473).

21542309887 is an equidigital number, since it uses as much as digits as its factorization.

21542309887 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9163 (or 9140 counting only the distinct ones).

The product of its (nonzero) digits is 967680, while the sum is 49.

The spelling of 21542309887 in words is "twenty-one billion, five hundred forty-two million, three hundred nine thousand, eight hundred eighty-seven".