70191721 has 4 divisors (see below), whose sum is σ = 70348500. Its totient is φ = 70034944.

The previous prime is 70191683. The next prime is 70191731. The reversal of 70191721 is 12719107.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 38887696 + 31304025 = 6236^2 + 5595^2 .

It is a cyclic number.

It is not a de Polignac number, because 70191721 - 2¹⁵ = 70158953 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 70191721.

It is not an unprimeable number, because it can be changed into a prime (70191731) 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, 77716 + ... + 78613.

It is an arithmetic number, because the mean of its divisors is an integer number (17587125).

Almost surely, 2^70191721 is an apocalyptic number.

It is an amenable number.

70191721 is a deficient number, since it is larger than the sum of its proper divisors (156779).

70191721 is a wasteful number, since it uses less digits than its factorization.

70191721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 156778.

The product of its (nonzero) digits is 882, while the sum is 28.

The square root of 70191721 is about 8378.0499521070. The cubic root of 70191721 is about 412.5044426825.

The spelling of 70191721 in words is "seventy million, one hundred ninety-one thousand, seven hundred twenty-one".