2161980021 has 16 divisors (see below), whose sum is σ = 2992091648. Its totient is φ = 1387108800.

The previous prime is 2161980019. The next prime is 2161980031. The reversal of 2161980021 is 1200891612.

It is a happy number.

It is not a de Polignac number, because 2161980021 - 2¹ = 2161980019 is a prime.

It is a super-2 number, since 2×2161980021² = 9348315222406320882, 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 (2161980031) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 47386 + ... + 81051.

It is an arithmetic number, because the mean of its divisors is an integer number (187005728).

Almost surely, 2^2161980021 is an apocalyptic number.

It is an amenable number.

2161980021 is a deficient number, since it is larger than the sum of its proper divisors (830111627).

2161980021 is a wasteful number, since it uses less digits than its factorization.

2161980021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 128652.

The product of its (nonzero) digits is 1728, while the sum is 30.

The square root of 2161980021 is about 46497.0969093770. The cubic root of 2161980021 is about 1293.0556772721.

The spelling of 2161980021 in words is "two billion, one hundred sixty-one million, nine hundred eighty thousand, twenty-one".