21025423 has 2 divisors, whose sum is σ = 21025424. Its totient is φ = 21025422.

The previous prime is 21025399. The next prime is 21025439. The reversal of 21025423 is 32452012.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21025423 - 2⁹ = 21024911 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21025423.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21005423) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10512711 + 10512712.

It is an arithmetic number, because the mean of its divisors is an integer number (10512712).

Almost surely, 2^21025423 is an apocalyptic number.

21025423 is a deficient number, since it is larger than the sum of its proper divisors (1).

21025423 is an equidigital number, since it uses as much as digits as its factorization.

21025423 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 480, while the sum is 19.

The square root of 21025423 is about 4585.3487326484. The cubic root of 21025423 is about 276.0037062794.

Adding to 21025423 its reverse (32452012), we get a palindrome (53477435).

The spelling of 21025423 in words is "twenty-one million, twenty-five thousand, four hundred twenty-three".