121805890 has 16 divisors (see below), whose sum is σ = 220070520. Its totient is φ = 48540160.

The previous prime is 121805791. The next prime is 121805891. The reversal of 121805890 is 98508121.

It can be written as a sum of positive squares in 4 ways, for example, as 91412721 + 30393169 = 9561^2 + 5513^2 .

It is not an unprimeable number, because it can be changed into a prime (121805891) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 19951 + ... + 25330.

Almost surely, 2^121805890 is an apocalyptic number.

121805890 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

121805890 is a deficient number, since it is larger than the sum of its proper divisors (98264630).

121805890 is a wasteful number, since it uses less digits than its factorization.

121805890 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 45557.

The product of its (nonzero) digits is 5760, while the sum is 34.

The square root of 121805890 is about 11036.5705724197. The cubic root of 121805890 is about 495.7043877832.

The spelling of 121805890 in words is "one hundred twenty-one million, eight hundred five thousand, eight hundred ninety".