21012023 has 4 divisors (see below), whose sum is σ = 21177600. Its totient is φ = 20846448.

The previous prime is 21011981. The next prime is 21012053. The reversal of 21012023 is 32021012.

It is a happy number.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 21012023 - 2⁶ = 21011959 is a prime.

It is a super-2 number, since 2×21012023² = 883010221105058, which contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21011995 and 21012013.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21012053) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 82598 + ... + 82851.

It is an arithmetic number, because the mean of its divisors is an integer number (5294400).

Almost surely, 2^21012023 is an apocalyptic number.

21012023 is a deficient number, since it is larger than the sum of its proper divisors (165577).

21012023 is a wasteful number, since it uses less digits than its factorization.

21012023 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 165576.

The product of its (nonzero) digits is 24, while the sum is 11.

The square root of 21012023 is about 4583.8873240951. The cubic root of 21012023 is about 275.9450592525.

Adding to 21012023 its reverse (32021012), we get a palindrome (53033035).

The spelling of 21012023 in words is "twenty-one million, twelve thousand, twenty-three".