21251023 has 2 divisors, whose sum is σ = 21251024. Its totient is φ = 21251022.

The previous prime is 21251017. The next prime is 21251053. The reversal of 21251023 is 32015212.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21251023 - 2⁹ = 21250511 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21250988 and 21251006.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21251053) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10625511 + 10625512.

It is an arithmetic number, because the mean of its divisors is an integer number (10625512).

Almost surely, 2^21251023 is an apocalyptic number.

21251023 is a deficient number, since it is larger than the sum of its proper divisors (1).

21251023 is an equidigital number, since it uses as much as digits as its factorization.

21251023 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 120, while the sum is 16.

The square root of 21251023 is about 4609.8831872402. The cubic root of 21251023 is about 276.9873575275.

Adding to 21251023 its reverse (32015212), we get a palindrome (53266235).

The spelling of 21251023 in words is "twenty-one million, two hundred fifty-one thousand, twenty-three".