21133021 has 24 divisors (see below), whose sum is σ = 27251840. Its totient is φ = 15957216.

The previous prime is 21133009. The next prime is 21133027. The reversal of 21133021 is 12033112.

21133021 = T₂₄₉ + T₂₅₀ + ... + T₅₂₁.

It is not a de Polignac number, because 21133021 - 2⁷ = 21132893 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (13).

It is a junction number, because it is equal to n+sod(n) for n = 21132992 and 21133010.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21133027) 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, 47920 + ... + 48358.

Almost surely, 2^21133021 is an apocalyptic number.

It is an amenable number.

21133021 is a deficient number, since it is larger than the sum of its proper divisors (6118819).

21133021 is a wasteful number, since it uses less digits than its factorization.

21133021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 505 (or 482 counting only the distinct ones).

The product of its (nonzero) digits is 36, while the sum is 13.

The square root of 21133021 is about 4597.0665646693. The cubic root of 21133021 is about 276.4737234779.

Adding to 21133021 its reverse (12033112), we get a palindrome (33166133).

Subtracting from 21133021 its reverse (12033112), we obtain a palindrome (9099909).

The spelling of 21133021 in words is "twenty-one million, one hundred thirty-three thousand, twenty-one".