21100023 has 24 divisors (see below), whose sum is σ = 36036000. Its totient is φ = 11640384.

The previous prime is 21100021. The next prime is 21100033. The reversal of 21100023 is 32000112.

It is a happy number.

It is not a de Polignac number, because 21100023 - 2¹ = 21100021 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (9).

It is a junction number, because it is equal to n+sod(n) for n = 21099978 and 21100014.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21100021) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 3948 + ... + 7601.

It is an arithmetic number, because the mean of its divisors is an integer number (1501500).

Almost surely, 2^21100023 is an apocalyptic number.

21100023 is a deficient number, since it is larger than the sum of its proper divisors (14935977).

21100023 is a wasteful number, since it uses less digits than its factorization.

21100023 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 11591 (or 11588 counting only the distinct ones).

The product of its (nonzero) digits is 12, while the sum is 9.

The square root of 21100023 is about 4593.4761346936. The cubic root of 21100023 is about 276.3297492296.

Adding to 21100023 its reverse (32000112), we get a palindrome (53100135).

The spelling of 21100023 in words is "twenty-one million, one hundred thousand, twenty-three".