135970721 has 4 divisors (see below), whose sum is σ = 136615344. Its totient is φ = 135326100.

The previous prime is 135970717. The next prime is 135970739. The reversal of 135970721 is 127079531.

It is a happy number.

135970721 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 135970721 - 2² = 135970717 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (135970621) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 321995 + ... + 322416.

It is an arithmetic number, because the mean of its divisors is an integer number (34153836).

Almost surely, 2^135970721 is an apocalyptic number.

It is an amenable number.

135970721 is a deficient number, since it is larger than the sum of its proper divisors (644623).

135970721 is an equidigital number, since it uses as much as digits as its factorization.

135970721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 644622.

The product of its (nonzero) digits is 13230, while the sum is 35.

The square root of 135970721 is about 11660.6483953509. The cubic root of 135970721 is about 514.2194112900.

The spelling of 135970721 in words is "one hundred thirty-five million, nine hundred seventy thousand, seven hundred twenty-one".