2129978 has 4 divisors (see below), whose sum is σ = 3194970. Its totient is φ = 1064988.

The previous prime is 2129977. The next prime is 2129983. The reversal of 2129978 is 8799212.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in only one way, i.e., 2111209 + 18769 = 1453^2 + 137^2 .

It is a d-powerful number, because it can be written as 2⁵ + 1 + 2²¹ + 9 + 9 + 7 + 8⁵ .

It is not an unprimeable number, because it can be changed into a prime (2129971) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 532493 + ... + 532496.

2^2129978 is an apocalyptic number.

2129978 is a deficient number, since it is larger than the sum of its proper divisors (1064992).

2129978 is a wasteful number, since it uses less digits than its factorization.

2129978 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1064991.

The product of its digits is 18144, while the sum is 38.

The square root of 2129978 is about 1459.4444148374. Note that the first 4 decimals coincide. The cubic root of 2129978 is about 128.6643921433.

The spelling of 2129978 in words is "two million, one hundred twenty-nine thousand, nine hundred seventy-eight".