21100423 has 2 divisors, whose sum is σ = 21100424. Its totient is φ = 21100422.

The previous prime is 21100411. The next prime is 21100441. The reversal of 21100423 is 32400112.

It is a weak prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21100423 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21100403) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10550211 + 10550212.

It is an arithmetic number, because the mean of its divisors is an integer number (10550212).

Almost surely, 2^21100423 is an apocalyptic number.

21100423 is a deficient number, since it is larger than the sum of its proper divisors (1).

21100423 is an equidigital number, since it uses as much as digits as its factorization.

21100423 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 48, while the sum is 13.

The square root of 21100423 is about 4593.5196744980. The cubic root of 21100423 is about 276.3314953762.

Adding to 21100423 its reverse (32400112), we get a palindrome (53500535).

The spelling of 21100423 in words is "twenty-one million, one hundred thousand, four hundred twenty-three".