21738131 has 2 divisors, whose sum is σ = 21738132. Its totient is φ = 21738130.

The previous prime is 21738127. The next prime is 21738133. The reversal of 21738131 is 13183712.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21738131 - 2² = 21738127 is a prime.

It is a super-2 number, since 2×21738131² = 945092678746322, which contains 22 as substring.

Together with 21738133, it forms a pair of twin primes.

It is a Chen prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21738131.

It is not a weakly prime, because it can be changed into another prime (21738133) 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 as a sum of consecutive naturals, namely, 10869065 + 10869066.

It is an arithmetic number, because the mean of its divisors is an integer number (10869066).

Almost surely, 2^21738131 is an apocalyptic number.

21738131 is a deficient number, since it is larger than the sum of its proper divisors (1).

21738131 is an equidigital number, since it uses as much as digits as its factorization.

21738131 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1008, while the sum is 26.

The square root of 21738131 is about 4662.4168625296. The cubic root of 21738131 is about 279.0877239424.

The spelling of 21738131 in words is "twenty-one million, seven hundred thirty-eight thousand, one hundred thirty-one".