21551143 has 2 divisors, whose sum is σ = 21551144. Its totient is φ = 21551142.

The previous prime is 21551137. The next prime is 21551171. The reversal of 21551143 is 34115512.

It is a happy number.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21551143 - 2¹³ = 21542951 is a prime.

It is equal to p_1362604 and since 21551143 and 1362604 have the same sum of digits, it is a Honaker prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21551113) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10775571 + 10775572.

It is an arithmetic number, because the mean of its divisors is an integer number (10775572).

Almost surely, 2^21551143 is an apocalyptic number.

21551143 is a deficient number, since it is larger than the sum of its proper divisors (1).

21551143 is an equidigital number, since it uses as much as digits as its factorization.

21551143 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 600, while the sum is 22.

The square root of 21551143 is about 4642.3208635337. The cubic root of 21551143 is about 278.2851954790.

Adding to 21551143 its reverse (34115512), we get a palindrome (55666655).

The spelling of 21551143 in words is "twenty-one million, five hundred fifty-one thousand, one hundred forty-three".