72270721 has 4 divisors (see below), whose sum is σ = 72293332. Its totient is φ = 72248112.

The previous prime is 72270719. The next prime is 72270743. The reversal of 72270721 is 12707227.

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 61779600 + 10491121 = 7860^2 + 3239^2 .

It is a cyclic number.

It is not a de Polignac number, because 72270721 - 2¹ = 72270719 is a prime.

It is a super-2 number, since 2×72270721² = 10446114227719682, which contains 22 as substring.

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 72270721.

It is not an unprimeable number, because it can be changed into a prime (72270521) 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 3 ways as a sum of consecutive naturals, for example, 5526 + ... + 13231.

It is an arithmetic number, because the mean of its divisors is an integer number (18073333).

Almost surely, 2^72270721 is an apocalyptic number.

It is an amenable number.

72270721 is a deficient number, since it is larger than the sum of its proper divisors (22611).

72270721 is a wasteful number, since it uses less digits than its factorization.

72270721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 22610.

The product of its (nonzero) digits is 2744, while the sum is 28.

The square root of 72270721 is about 8501.2187949729. The cubic root of 72270721 is about 416.5375220739.

Adding to 72270721 its reverse (12707227), we get a palindrome (84977948).

The spelling of 72270721 in words is "seventy-two million, two hundred seventy thousand, seven hundred twenty-one".