21420001242 has 48 divisors (see below), whose sum is σ = 48038095872. Its totient is φ = 6890784480.

The previous prime is 21420001181. The next prime is 21420001247. The reversal of 21420001242 is 24210002412.

21420001242 is a `hidden beast` number, since 2 + 1 + 420 + 0 + 0 + 1 + 242 = 666.

It is a Harshad number since it is a multiple of its sum of digits (18).

It is not an unprimeable number, because it can be changed into a prime (21420001247) 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, 152488 + ... + 257084.

It is an arithmetic number, because the mean of its divisors is an integer number (1000793664).

Almost surely, 2^21420001242 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21420001242, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (24019047936).

21420001242 is an abundant number, since it is smaller than the sum of its proper divisors (26618094630).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21420001242 is a wasteful number, since it uses less digits than its factorization.

21420001242 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 105003 (or 105000 counting only the distinct ones).

The product of its (nonzero) digits is 256, while the sum is 18.

Adding to 21420001242 its reverse (24210002412), we get a palindrome (45630003654).

The spelling of 21420001242 in words is "twenty-one billion, four hundred twenty million, one thousand, two hundred forty-two".