20400355421 has 4 divisors (see below), whose sum is σ = 20408918592. Its totient is φ = 20391792252.

The previous prime is 20400355387. The next prime is 20400355429. The reversal of 20400355421 is 12455300402.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 20400355421 - 2⁶ = 20400355357 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20400355429) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 4278011 + ... + 4282776.

It is an arithmetic number, because the mean of its divisors is an integer number (5102229648).

Almost surely, 2^20400355421 is an apocalyptic number.

It is an amenable number.

20400355421 is a deficient number, since it is larger than the sum of its proper divisors (8563171).

20400355421 is an equidigital number, since it uses as much as digits as its factorization.

20400355421 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8563170.

The product of its (nonzero) digits is 4800, while the sum is 26.

Adding to 20400355421 its reverse (12455300402), we get a palindrome (32855655823).

The spelling of 20400355421 in words is "twenty billion, four hundred million, three hundred fifty-five thousand, four hundred twenty-one".