21171023 has 2 divisors, whose sum is σ = 21171024. Its totient is φ = 21171022.

The previous prime is 21170987. The next prime is 21171037. The reversal of 21171023 is 32017112.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21171023 - 2¹² = 21166927 is a prime.

It is a super-3 number, since 3×21171023³ (a number of 23 digits) contains 333 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 21170992 and 21171010.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21171043) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10585511 + 10585512.

It is an arithmetic number, because the mean of its divisors is an integer number (10585512).

Almost surely, 2^21171023 is an apocalyptic number.

21171023 is a deficient number, since it is larger than the sum of its proper divisors (1).

21171023 is an equidigital number, since it uses as much as digits as its factorization.

21171023 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 84, while the sum is 17.

The square root of 21171023 is about 4601.1979961745. The cubic root of 21171023 is about 276.6393452158.

Adding to 21171023 its reverse (32017112), we get a palindrome (53188135).

The spelling of 21171023 in words is "twenty-one million, one hundred seventy-one thousand, twenty-three".