21400423423 has 2 divisors, whose sum is σ = 21400423424. Its totient is φ = 21400423422.

The previous prime is 21400423381. The next prime is 21400423453. The reversal of 21400423423 is 32432400412.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21400423423 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21400423453) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10700211711 + 10700211712.

It is an arithmetic number, because the mean of its divisors is an integer number (10700211712).

Almost surely, 2^21400423423 is an apocalyptic number.

21400423423 is a deficient number, since it is larger than the sum of its proper divisors (1).

21400423423 is an equidigital number, since it uses as much as digits as its factorization.

21400423423 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 4608, while the sum is 25.

Adding to 21400423423 its reverse (32432400412), we get a palindrome (53832823835).

The spelling of 21400423423 in words is "twenty-one billion, four hundred million, four hundred twenty-three thousand, four hundred twenty-three".