21138117 has 32 divisors (see below), whose sum is σ = 37847040. Its totient is φ = 10134720.

The previous prime is 21138113. The next prime is 21138121. The reversal of 21138117 is 71183112.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (21138113) and next prime (21138121).

It is not a de Polignac number, because 21138117 - 2² = 21138113 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21138113) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 517 + ... + 6522.

It is an arithmetic number, because the mean of its divisors is an integer number (1182720).

Almost surely, 2^21138117 is an apocalyptic number.

It is an amenable number.

21138117 is a deficient number, since it is larger than the sum of its proper divisors (16708923).

21138117 is a wasteful number, since it uses less digits than its factorization.

21138117 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7073.

The product of its digits is 336, while the sum is 24.

The square root of 21138117 is about 4597.6207977605. The cubic root of 21138117 is about 276.4959445770.

The spelling of 21138117 in words is "twenty-one million, one hundred thirty-eight thousand, one hundred seventeen".