21123400401 has 20 divisors (see below), whose sum is σ = 31559098032. Its totient is φ = 14080308408.

The previous prime is 21123400391. The next prime is 21123400421. The reversal of 21123400401 is 10400432112.

It is not a de Polignac number, because 21123400401 - 2⁷ = 21123400273 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21123400421) by changing a digit.

It is a polite number, since it can be written in 19 ways as a sum of consecutive naturals, for example, 787330 + ... + 813716.

Almost surely, 2^21123400401 is an apocalyptic number.

It is an amenable number.

21123400401 is a deficient number, since it is larger than the sum of its proper divisors (10435697631).

21123400401 is an equidigital number, since it uses as much as digits as its factorization.

21123400401 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 36282 (or 36273 counting only the distinct ones).

The product of its (nonzero) digits is 192, while the sum is 18.

Adding to 21123400401 its reverse (10400432112), we get a palindrome (31523832513).

The spelling of 21123400401 in words is "twenty-one billion, one hundred twenty-three million, four hundred thousand, four hundred one".