1221890 has 32 divisors (see below), whose sum is σ = 2376000. Its totient is φ = 451008.

The previous prime is 1221863. The next prime is 1221907. The reversal of 1221890 is 981221.

It is a Curzon number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 11156 + ... + 11264.

It is an arithmetic number, because the mean of its divisors is an integer number (74250).

2^1221890 is an apocalyptic number.

1221890 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

1221890 is a deficient number, since it is larger than the sum of its proper divisors (1154110).

1221890 is a wasteful number, since it uses less digits than its factorization.

1221890 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 194.

The product of its (nonzero) digits is 288, while the sum is 23.

The square root of 1221890 is about 1105.3913334200. The cubic root of 1221890 is about 106.9081227203.

The spelling of 1221890 in words is "one million, two hundred twenty-one thousand, eight hundred ninety".