2161696121 has 4 divisors (see below), whose sum is σ = 2327980452. Its totient is φ = 1995411792.

The previous prime is 2161696091. The next prime is 2161696153. The reversal of 2161696121 is 1216961612.

2161696121 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

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 442681600 + 1719014521 = 21040^2 + 41461^2 .

It is a cyclic number.

It is not a de Polignac number, because 2161696121 - 2²² = 2157501817 is a prime.

It is an alternating number because its digits alternate between even and odd.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (2161696181) 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, 83142146 + ... + 83142171.

It is an arithmetic number, because the mean of its divisors is an integer number (581995113).

Almost surely, 2^2161696121 is an apocalyptic number.

It is an amenable number.

2161696121 is a deficient number, since it is larger than the sum of its proper divisors (166284331).

2161696121 is a wasteful number, since it uses less digits than its factorization.

2161696121 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 166284330.

The product of its digits is 7776, while the sum is 35.

The square root of 2161696121 is about 46494.0439303789. The cubic root of 2161696121 is about 1292.9990756734. Note that the first 3 decimals are identical.

The spelling of 2161696121 in words is "two billion, one hundred sixty-one million, six hundred ninety-six thousand, one hundred twenty-one".