2161971 has 48 divisors (see below), whose sum is σ = 3913728. Its totient is φ = 1166400.

The previous prime is 2161967. The next prime is 2161987. The reversal of 2161971 is 1791612.

2161971 = T₁₈ + T₁₉ + ... + T₂₃₄.

It is not a de Polignac number, because 2161971 - 2² = 2161967 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (27).

2161971 is a lucky number.

It is not an unprimeable number, because it can be changed into a prime (2161571) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 52711 + ... + 52751.

It is an arithmetic number, because the mean of its divisors is an integer number (81536).

2^2161971 is an apocalyptic number.

2161971 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

2161971 is a deficient number, since it is larger than the sum of its proper divisors (1751757).

2161971 is an equidigital number, since it uses as much as digits as its factorization.

2161971 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 94 (or 82 counting only the distinct ones).

The product of its digits is 756, while the sum is 27.

The square root of 2161971 is about 1470.3642405880. The cubic root of 2161971 is about 129.3053878817.

It can be divided in two parts, 216 and 1971, that added together give a 7-th power (2187 = 3⁷).

The spelling of 2161971 in words is "two million, one hundred sixty-one thousand, nine hundred seventy-one".