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21139157 = 131626089
BaseRepresentation
bin101000010100…
…0111011010101
31110202222110202
41100220323111
520402423112
62033030245
7344452124
oct120507325
943688422
1021139157
1110a29186
1270b5385
1344c1aa0
142b43abb
151cc86c2
hex1428ed5

21139157 has 4 divisors (see below), whose sum is σ = 22765260. Its totient is φ = 19513056.

The previous prime is 21139127. The next prime is 21139159. The reversal of 21139157 is 75193112.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 988036 + 20151121 = 994^2 + 4489^2 .

It is a cyclic number.

It is not a de Polignac number, because 21139157 - 210 = 21138133 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 (21139159) 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, 813032 + ... + 813057.

It is an arithmetic number, because the mean of its divisors is an integer number (5691315).

Almost surely, 221139157 is an apocalyptic number.

It is an amenable number.

21139157 is a deficient number, since it is larger than the sum of its proper divisors (1626103).

21139157 is a wasteful number, since it uses less digits than its factorization.

21139157 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1626102.

The product of its digits is 1890, while the sum is 29.

The square root of 21139157 is about 4597.7338983460. The cubic root of 21139157 is about 276.5004790564.

The spelling of 21139157 in words is "twenty-one million, one hundred thirty-nine thousand, one hundred fifty-seven".

Divisors: 1 13 1626089 21139157