2151978 has 32 divisors (see below), whose sum is σ = 4646400. Its totient is φ = 662256.

The previous prime is 2151977. The next prime is 2151991. The reversal of 2151978 is 8791512.

It is not an unprimeable number, because it can be changed into a prime (2151971) 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, 4683 + ... + 5121.

It is an arithmetic number, because the mean of its divisors is an integer number (145200).

2^2151978 is an apocalyptic number.

2151978 is an abundant number, since it is smaller than the sum of its proper divisors (2494422).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

2151978 is a wasteful number, since it uses less digits than its factorization.

2151978 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 506.

The product of its digits is 5040, while the sum is 33.

The square root of 2151978 is about 1466.9621672013. The cubic root of 2151978 is about 129.1058562640.

The spelling of 2151978 in words is "two million, one hundred fifty-one thousand, nine hundred seventy-eight".