21133949 has 4 divisors (see below), whose sum is σ = 21218400. Its totient is φ = 21049500.

The previous prime is 21133939. The next prime is 21133961. The reversal of 21133949 is 94933112.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 21133949 - 2²⁴ = 4356733 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21133939) 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, 41849 + ... + 42350.

It is an arithmetic number, because the mean of its divisors is an integer number (5304600).

Almost surely, 2^21133949 is an apocalyptic number.

It is an amenable number.

21133949 is a deficient number, since it is larger than the sum of its proper divisors (84451).

21133949 is an equidigital number, since it uses as much as digits as its factorization.

21133949 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 84450.

The product of its digits is 5832, while the sum is 32.

The square root of 21133949 is about 4597.1674974923. The cubic root of 21133949 is about 276.4777702863.

The spelling of 21133949 in words is "twenty-one million, one hundred thirty-three thousand, nine hundred forty-nine".