135543721 has 2 divisors, whose sum is σ = 135543722. Its totient is φ = 135543720.

The previous prime is 135543719. The next prime is 135543787. The reversal of 135543721 is 127345531.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 106502400 + 29041321 = 10320^2 + 5389^2 .

It is a cyclic number.

It is not a de Polignac number, because 135543721 - 2¹ = 135543719 is a prime.

Together with 135543719, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (135543521) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 67771860 + 67771861.

It is an arithmetic number, because the mean of its divisors is an integer number (67771861).

Almost surely, 2^135543721 is an apocalyptic number.

It is an amenable number.

135543721 is a deficient number, since it is larger than the sum of its proper divisors (1).

135543721 is an equidigital number, since it uses as much as digits as its factorization.

135543721 is an evil number, because the sum of its binary digits is even.

The product of its digits is 12600, while the sum is 31.

The square root of 135543721 is about 11642.3245531122. The cubic root of 135543721 is about 513.6805650463.

The spelling of 135543721 in words is "one hundred thirty-five million, five hundred forty-three thousand, seven hundred twenty-one".