2121178406 has 4 divisors (see below), whose sum is σ = 3181767612. Its totient is φ = 1060589202.

The previous prime is 2121178403. The next prime is 2121178459. The reversal of 2121178406 is 6048711212.

It is a happy number.

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

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (2121178403) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 530294600 + ... + 530294603.

It is an arithmetic number, because the mean of its divisors is an integer number (795441903).

Almost surely, 2^2121178406 is an apocalyptic number.

2121178406 is a deficient number, since it is larger than the sum of its proper divisors (1060589206).

2121178406 is a wasteful number, since it uses less digits than its factorization.

2121178406 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1060589205.

The product of its (nonzero) digits is 5376, while the sum is 32.

The square root of 2121178406 is about 46056.2526265436. The cubic root of 2121178406 is about 1284.8696352681.

Adding to 2121178406 its reverse (6048711212), we get a palindrome (8169889618).

The spelling of 2121178406 in words is "two billion, one hundred twenty-one million, one hundred seventy-eight thousand, four hundred six".