10561721 has 4 divisors (see below), whose sum is σ = 10596432. Its totient is φ = 10527012.

The previous prime is 10561697. The next prime is 10561729. The reversal of 10561721 is 12716501.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 12716501 = 7 ⋅1816643.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-10561721 is a prime.

It is a super-2 number, since 2×10561721² = 223099900963682, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (10561729) 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, 16895 + ... + 17508.

It is an arithmetic number, because the mean of its divisors is an integer number (2649108).

Almost surely, 2^10561721 is an apocalyptic number.

It is an amenable number.

10561721 is a deficient number, since it is larger than the sum of its proper divisors (34711).

10561721 is an equidigital number, since it uses as much as digits as its factorization.

10561721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 34710.

The product of its (nonzero) digits is 420, while the sum is 23.

The square root of 10561721 is about 3249.8801516364. The cubic root of 10561721 is about 219.4041798237.

The spelling of 10561721 in words is "ten million, five hundred sixty-one thousand, seven hundred twenty-one".