135721540 has 24 divisors (see below), whose sum is σ = 301781592. Its totient is φ = 51095040.

The previous prime is 135721519. The next prime is 135721549. The reversal of 135721540 is 45127531.

It is a happy number.

It can be written as a sum of positive squares in 4 ways, for example, as 7941124 + 127780416 = 2818^2 + 11304^2 .

It is a junction number, because it is equal to n+sod(n) for n = 135721499 and 135721508.

It is not an unprimeable number, because it can be changed into a prime (135721549) 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 in 7 ways as a sum of consecutive naturals, for example, 199251 + ... + 199930.

It is an arithmetic number, because the mean of its divisors is an integer number (12574233).

Almost surely, 2^135721540 is an apocalyptic number.

135721540 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

135721540 is an abundant number, since it is smaller than the sum of its proper divisors (166060052).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

135721540 is a wasteful number, since it uses less digits than its factorization.

135721540 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 399207 (or 399205 counting only the distinct ones).

The product of its (nonzero) digits is 4200, while the sum is 28.

The square root of 135721540 is about 11649.9587982104. The cubic root of 135721540 is about 513.9050983779.

The spelling of 135721540 in words is "one hundred thirty-five million, seven hundred twenty-one thousand, five hundred forty".