21138004 has 24 divisors (see below), whose sum is σ = 39470760. Its totient is φ = 9870336.

The previous prime is 21137999. The next prime is 21138011. The reversal of 21138004 is 40083112.

It can be written as a sum of positive squares in 4 ways, for example, as 1795600 + 19342404 = 1340^2 + 4398^2 .

It is a plaindrome in base 7.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 8182 + ... + 10450.

It is an arithmetic number, because the mean of its divisors is an integer number (1644615).

Almost surely, 2^21138004 is an apocalyptic number.

It is an amenable number.

21138004 is a deficient number, since it is larger than the sum of its proper divisors (18332756).

21138004 is a wasteful number, since it uses less digits than its factorization.

21138004 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2427 (or 2425 counting only the distinct ones).

The product of its (nonzero) digits is 192, while the sum is 19.

The square root of 21138004 is about 4597.6085087793. The cubic root of 21138004 is about 276.4954518794.

The spelling of 21138004 in words is "twenty-one million, one hundred thirty-eight thousand, four".