2501161781 has 4 divisors (see below), whose sum is σ = 2526947052. Its totient is φ = 2475376512.

The previous prime is 2501161769. The next prime is 2501161783. The reversal of 2501161781 is 1871611052.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 1618774756 + 882387025 = 40234^2 + 29705^2 .

It is a cyclic number.

It is not a de Polignac number, because 2501161781 - 2¹⁰ = 2501160757 is a prime.

It is a super-2 number, since 2×2501161781² = 12511620509470183922, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (2501161783) 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, 12892490 + ... + 12892683.

It is an arithmetic number, because the mean of its divisors is an integer number (631736763).

Almost surely, 2^2501161781 is an apocalyptic number.

It is an amenable number.

2501161781 is a deficient number, since it is larger than the sum of its proper divisors (25785271).

2501161781 is an equidigital number, since it uses as much as digits as its factorization.

2501161781 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 25785270.

The product of its (nonzero) digits is 3360, while the sum is 32.

The square root of 2501161781 is about 50011.6164605784. The cubic root of 2501161781 is about 1357.4190129934.

The spelling of 2501161781 in words is "two billion, five hundred one million, one hundred sixty-one thousand, seven hundred eighty-one".