21103457 has 2 divisors, whose sum is σ = 21103458. Its totient is φ = 21103456.

The previous prime is 21103451. The next prime is 21103493. The reversal of 21103457 is 75430112.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 19018321 + 2085136 = 4361^2 + 1444^2 .

It is a cyclic number.

It is not a de Polignac number, because 21103457 - 2⁴ = 21103441 is a prime.

It is not a weakly prime, because it can be changed into another prime (21103451) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10551728 + 10551729.

It is an arithmetic number, because the mean of its divisors is an integer number (10551729).

Almost surely, 2^21103457 is an apocalyptic number.

It is an amenable number.

21103457 is a deficient number, since it is larger than the sum of its proper divisors (1).

21103457 is an equidigital number, since it uses as much as digits as its factorization.

21103457 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 840, while the sum is 23.

The square root of 21103457 is about 4593.8499104781. The cubic root of 21103457 is about 276.3447391798.

Adding to 21103457 its reverse (75430112), we get a palindrome (96533569).

The spelling of 21103457 in words is "twenty-one million, one hundred three thousand, four hundred fifty-seven".