21138033 has 16 divisors (see below), whose sum is σ = 32276480. Its totient is φ = 12054096.

The previous prime is 21138023. The next prime is 21138053. The reversal of 21138033 is 33083112.

It is a happy number.

It is not a de Polignac number, because 21138033 - 2⁴ = 21138017 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (21).

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21138023) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 15888 + ... + 17166.

It is an arithmetic number, because the mean of its divisors is an integer number (2017280).

Almost surely, 2^21138033 is an apocalyptic number.

It is an amenable number.

21138033 is a deficient number, since it is larger than the sum of its proper divisors (11138447).

21138033 is a wasteful number, since it uses less digits than its factorization.

21138033 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2076.

The product of its (nonzero) digits is 432, while the sum is 21.

The square root of 21138033 is about 4597.6116625918. The cubic root of 21138033 is about 276.4955783241.

The spelling of 21138033 in words is "twenty-one million, one hundred thirty-eight thousand, thirty-three".