20400240042 has 128 divisors (see below), whose sum is σ = 56131891200. Its totient is φ = 5347850688.

The previous prime is 20400239983. The next prime is 20400240083. The reversal of 20400240042 is 24004200402.

20400240042 is a `hidden beast` number, since 20 + 400 + 240 + 0 + 4 + 2 = 666.

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

It is a junction number, because it is equal to n+sod(n) for n = 20400239997 and 20400240024.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 808209 + ... + 833067.

It is an arithmetic number, because the mean of its divisors is an integer number (438530400).

Almost surely, 2^20400240042 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 20400240042, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (28065945600).

20400240042 is an abundant number, since it is smaller than the sum of its proper divisors (35731651158).

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

20400240042 is a wasteful number, since it uses less digits than its factorization.

20400240042 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 25057 (or 25051 counting only the distinct ones).

The product of its (nonzero) digits is 512, while the sum is 18.

Adding to 20400240042 its reverse (24004200402), we get a palindrome (44404440444).

The spelling of 20400240042 in words is "twenty billion, four hundred million, two hundred forty thousand, forty-two".