2156904 has 48 divisors (see below), whose sum is σ = 6048900. Its totient is φ = 693504.

The previous prime is 2156897. The next prime is 2156939. The reversal of 2156904 is 4096512.

Added to its reverse (4096512) it gives a triangular number (6253416 = T₃₅₃₆).

It can be written as a sum of positive squares in 2 ways, for example, as 1954404 + 202500 = 1398^2 + 450^2 .

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 1572 + ... + 2604.

2^2156904 is an apocalyptic number.

2156904 is a gapful number since it is divisible by the number (24) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 2156904, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (3024450).

2156904 is an abundant number, since it is smaller than the sum of its proper divisors (3891996).

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

2156904 is a wasteful number, since it uses less digits than its factorization.

2156904 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1074 (or 1067 counting only the distinct ones).

The product of its (nonzero) digits is 2160, while the sum is 27.

The square root of 2156904 is about 1468.6401873842. The cubic root of 2156904 is about 129.2042914095.

Adding to 2156904 its reverse (4096512), we get a triangular number (6253416 = T₃₅₃₆).

The spelling of 2156904 in words is "two million, one hundred fifty-six thousand, nine hundred four".