20400002540 has 48 divisors (see below), whose sum is σ = 44033691072. Its totient is φ = 7932992256.

The previous prime is 20400002461. The next prime is 20400002549. The reversal of 20400002540 is 4520000402.

It is not an unprimeable number, because it can be changed into a prime (20400002549) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 953642 + ... + 974798.

It is an arithmetic number, because the mean of its divisors is an integer number (917368564).

Almost surely, 2^20400002540 is an apocalyptic number.

20400002540 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 20400002540, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (22016845536).

20400002540 is an abundant number, since it is smaller than the sum of its proper divisors (23633688532).

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

20400002540 is a wasteful number, since it uses less digits than its factorization.

20400002540 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 22506 (or 22504 counting only the distinct ones).

The product of its (nonzero) digits is 320, while the sum is 17.

Adding to 20400002540 its reverse (4520000402), we get a palindrome (24920002942).

The spelling of 20400002540 in words is "twenty billion, four hundred million, two thousand, five hundred forty".