1051720561 has 4 divisors (see below), whose sum is σ = 1077372324. Its totient is φ = 1026068800.

The previous prime is 1051720529. The next prime is 1051720567. The reversal of 1051720561 is 1650271501.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 1650271501 = 43 ⋅38378407.

It can be written as a sum of positive squares in 2 ways, for example, as 272250000 + 779470561 = 16500^2 + 27919^2 .

It is a cyclic number.

It is not a de Polignac number, because 1051720561 - 2⁵ = 1051720529 is a prime.

It is a super-2 number, since 2×1051720561² = 2212232276860309442, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1051720567) 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, 12825820 + ... + 12825901.

It is an arithmetic number, because the mean of its divisors is an integer number (269343081).

Almost surely, 2^1051720561 is an apocalyptic number.

It is an amenable number.

1051720561 is a deficient number, since it is larger than the sum of its proper divisors (25651763).

1051720561 is an equidigital number, since it uses as much as digits as its factorization.

1051720561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 25651762.

The product of its (nonzero) digits is 2100, while the sum is 28.

The square root of 1051720561 is about 32430.2414576272. The cubic root of 1051720561 is about 1016.9512195464.

The spelling of 1051720561 in words is "one billion, fifty-one million, seven hundred twenty thousand, five hundred sixty-one".