21010023 has 12 divisors (see below), whose sum is σ = 31472168. Its totient is φ = 14006520.

The previous prime is 21010013. The next prime is 21010037. The reversal of 21010023 is 32001012.

It is a happy number.

It is not a de Polignac number, because 21010023 - 2¹³ = 21001831 is a prime.

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

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21009987 and 21010014.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21010013) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 42988 + ... + 43473.

Almost surely, 2^21010023 is an apocalyptic number.

21010023 is a deficient number, since it is larger than the sum of its proper divisors (10462145).

21010023 is an frugal number, since it uses more digits than its factorization.

21010023 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 86476 (or 86464 counting only the distinct ones).

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

The square root of 21010023 is about 4583.6691634541. The cubic root of 21010023 is about 275.9363038266.

Adding to 21010023 its reverse (32001012), we get a palindrome (53011035).

It can be divided in two parts, 2 and 1010023, that added together give a square (1010025 = 1005²).

The spelling of 21010023 in words is "twenty-one million, ten thousand, twenty-three".