2161507021 has 4 divisors (see below), whose sum is σ = 2161787292. Its totient is φ = 2161226752.

The previous prime is 2161506983. The next prime is 2161507027. The reversal of 2161507021 is 1207051612.

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 1319868900 + 841638121 = 36330^2 + 29011^2 .

It is a cyclic number.

It is not a de Polignac number, because 2161507021 - 2¹⁵ = 2161474253 is a prime.

It is a super-2 number, since 2×2161507021² = 9344225203664588882, 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 (2161507027) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 128230 + ... + 144103.

It is an arithmetic number, because the mean of its divisors is an integer number (540446823).

Almost surely, 2^2161507021 is an apocalyptic number.

It is an amenable number.

2161507021 is a deficient number, since it is larger than the sum of its proper divisors (280271).

2161507021 is an equidigital number, since it uses as much as digits as its factorization.

2161507021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 280270.

The product of its (nonzero) digits is 840, while the sum is 25.

The square root of 2161507021 is about 46492.0102920921. The cubic root of 2161507021 is about 1292.9613717531.

Adding to 2161507021 its reverse (1207051612), we get a palindrome (3368558633).

The spelling of 2161507021 in words is "two billion, one hundred sixty-one million, five hundred seven thousand, twenty-one".