21138411 has 16 divisors (see below), whose sum is σ = 32997888. Its totient is φ = 11784000.

The previous prime is 21138409. The next prime is 21138421. The reversal of 21138411 is 11483112.

It is a happy number.

It is not a de Polignac number, because 21138411 - 2¹ = 21138409 is a prime.

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

It is not an unprimeable number, because it can be changed into a prime (21138401) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 11415 + ... + 13136.

It is an arithmetic number, because the mean of its divisors is an integer number (2062368).

Almost surely, 2^21138411 is an apocalyptic number.

21138411 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

21138411 is a deficient number, since it is larger than the sum of its proper divisors (11859477).

21138411 is a wasteful number, since it uses less digits than its factorization.

21138411 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 24602.

The product of its digits is 192, while the sum is 21.

The square root of 21138411 is about 4597.6527707081. The cubic root of 21138411 is about 276.4972264545.

The spelling of 21138411 in words is "twenty-one million, one hundred thirty-eight thousand, four hundred eleven".