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31388381 is a prime number
BaseRepresentation
bin111011110111…
…1001011011101
32012001200202122
41313233023131
531013412011
63040432325
7530540213
oct167571335
965050678
1031388381
1116799612
12a6186a5
13666cc0b
144250cb3
152b503db
hex1def2dd

31388381 has 2 divisors, whose sum is σ = 31388382. Its totient is φ = 31388380.

The previous prime is 31388377. The next prime is 31388387. The reversal of 31388381 is 18388313.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 25908100 + 5480281 = 5090^2 + 2341^2 .

It is a cyclic number.

It is not a de Polignac number, because 31388381 - 22 = 31388377 is a prime.

It is a super-2 number, since 2×313883812 = 1970460923602322, which contains 22 as substring.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (31388387) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 15694190 + 15694191.

It is an arithmetic number, because the mean of its divisors is an integer number (15694191).

Almost surely, 231388381 is an apocalyptic number.

It is an amenable number.

31388381 is a deficient number, since it is larger than the sum of its proper divisors (1).

31388381 is an equidigital number, since it uses as much as digits as its factorization.

31388381 is an evil number, because the sum of its binary digits is even.

The product of its digits is 13824, while the sum is 35.

The square root of 31388381 is about 5602.5334447908. The cubic root of 31388381 is about 315.4445089152. Note that the first 3 decimals are identical.

The spelling of 31388381 in words is "thirty-one million, three hundred eighty-eight thousand, three hundred eighty-one".