1220500721 has 16 divisors (see below), whose sum is σ = 1393790976. Its totient is φ = 1058610000.

The previous prime is 1220500717. The next prime is 1220500733. The reversal of 1220500721 is 1270050221.

It is not a de Polignac number, because 1220500721 - 2² = 1220500717 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 1220500693 and 1220500702.

It is not an unprimeable number, because it can be changed into a prime (1220500711) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 995 + ... + 49416.

It is an arithmetic number, because the mean of its divisors is an integer number (87111936).

Almost surely, 2^1220500721 is an apocalyptic number.

1220500721 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

It is an amenable number.

1220500721 is a deficient number, since it is larger than the sum of its proper divisors (173290255).

1220500721 is a wasteful number, since it uses less digits than its factorization.

1220500721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 50524.

The product of its (nonzero) digits is 280, while the sum is 20.

The square root of 1220500721 is about 34935.6654580960. The cubic root of 1220500721 is about 1068.6758946554.

Adding to 1220500721 its reverse (1270050221), we get a palindrome (2490550942).

It can be divided in two parts, 1220500 and 721, that added together give a palindrome (1221221).

The spelling of 1220500721 in words is "one billion, two hundred twenty million, five hundred thousand, seven hundred twenty-one".