71220721 has 24 divisors (see below), whose sum is σ = 88780160. Its totient is φ = 56596320.

The previous prime is 71220713. The next prime is 71220727. The reversal of 71220721 is 12702217.

It is not a de Polignac number, because 71220721 - 2³ = 71220713 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 71220692 and 71220701.

It is not an unprimeable number, because it can be changed into a prime (71220727) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 28696 + ... + 31078.

Almost surely, 2^71220721 is an apocalyptic number.

It is an amenable number.

71220721 is a deficient number, since it is larger than the sum of its proper divisors (17559439).

71220721 is a wasteful number, since it uses less digits than its factorization.

71220721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2437 (or 2426 counting only the distinct ones).

The product of its (nonzero) digits is 392, while the sum is 22.

The square root of 71220721 is about 8439.2369915769. The cubic root of 71220721 is about 414.5104228161.

Adding to 71220721 its reverse (12702217), we get a palindrome (83922938).

The spelling of 71220721 in words is "seventy-one million, two hundred twenty thousand, seven hundred twenty-one".