2121780 has 24 divisors (see below), whose sum is σ = 5941152. Its totient is φ = 565792.

The previous prime is 2121767. The next prime is 2121781. The reversal of 2121780 is 871212.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (2121781) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 17622 + ... + 17741.

It is an arithmetic number, because the mean of its divisors is an integer number (247548).

2^2121780 is an apocalyptic number.

2121780 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

2121780 is an abundant number, since it is smaller than the sum of its proper divisors (3819372).

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

2121780 is a wasteful number, since it uses less digits than its factorization.

2121780 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 35375 (or 35373 counting only the distinct ones).

The product of its (nonzero) digits is 224, while the sum is 21.

The square root of 2121780 is about 1456.6331041137. The cubic root of 2121780 is about 128.4991092410.

Adding to 2121780 its reverse (871212), we get a palindrome (2992992).

The spelling of 2121780 in words is "two million, one hundred twenty-one thousand, seven hundred eighty".