20400042400 has 36 divisors (see below), whose sum is σ = 49801605462. Its totient is φ = 8160016640.

The previous prime is 20400042391. The next prime is 20400042401. The reversal of 20400042400 is 424000402.

It can be written as a sum of positive squares in 3 ways, for example, as 16815864976 + 3584177424 = 129676^2 + 59868^2 .

It is a Harshad number since it is a multiple of its sum of digits (16).

It is not an unprimeable number, because it can be changed into a prime (20400042401) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 12749227 + ... + 12750826.

Almost surely, 2^20400042400 is an apocalyptic number.

20400042400 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

20400042400 is an abundant number, since it is smaller than the sum of its proper divisors (29401563062).

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

20400042400 is a wasteful number, since it uses less digits than its factorization.

20400042400 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 25500073 (or 25500060 counting only the distinct ones).

The product of its (nonzero) digits is 256, while the sum is 16.

Adding to 20400042400 its reverse (424000402), we get a palindrome (20824042802).

The spelling of 20400042400 in words is "twenty billion, four hundred million, forty-two thousand, four hundred".