21553123 has 2 divisors, whose sum is σ = 21553124. Its totient is φ = 21553122.

The previous prime is 21553111. The next prime is 21553141. The reversal of 21553123 is 32135512.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21553123 - 2¹³ = 21544931 is a prime.

It is a super-2 number, since 2×21553123² = 929074222106258, which contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 21553094 and 21553103.

It is not a weakly prime, because it can be changed into another prime (21553183) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10776561 + 10776562.

It is an arithmetic number, because the mean of its divisors is an integer number (10776562).

Almost surely, 2^21553123 is an apocalyptic number.

21553123 is a deficient number, since it is larger than the sum of its proper divisors (1).

21553123 is an equidigital number, since it uses as much as digits as its factorization.

21553123 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 900, while the sum is 22.

The square root of 21553123 is about 4642.5341140373. The cubic root of 21553123 is about 278.2937176536.

Adding to 21553123 its reverse (32135512), we get a palindrome (53688635).

The spelling of 21553123 in words is "twenty-one million, five hundred fifty-three thousand, one hundred twenty-three".