1056217721 has 6 divisors (see below), whose sum is σ = 1143715230. Its totient is φ = 974970048.

The previous prime is 1056217703. The next prime is 1056217741. The reversal of 1056217721 is 1277126501.

It can be written as a sum of positive squares in 3 ways, for example, as 43705321 + 1012512400 = 6611^2 + 31820^2 .

It is a de Polignac number, because none of the positive numbers 2^k-1056217721 is a prime.

It is a super-2 number, since 2×1056217721² = 2231191748308867682, which contains 22 as substring.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (1056217741) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 3124736 + ... + 3125073.

It is an arithmetic number, because the mean of its divisors is an integer number (190619205).

Almost surely, 2^1056217721 is an apocalyptic number.

It is an amenable number.

1056217721 is a deficient number, since it is larger than the sum of its proper divisors (87497509).

1056217721 is an equidigital number, since it uses as much as digits as its factorization.

1056217721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6249835 (or 6249822 counting only the distinct ones).

The product of its (nonzero) digits is 5880, while the sum is 32.

The square root of 1056217721 is about 32499.5033962059. The cubic root of 1056217721 is about 1018.3986538251.

The spelling of 1056217721 in words is "one billion, fifty-six million, two hundred seventeen thousand, seven hundred twenty-one".