9921890 has 16 divisors (see below), whose sum is σ = 19483200. Its totient is φ = 3607920.

The previous prime is 9921889. The next prime is 9921907. The reversal of 9921890 is 981299.

9921890 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 44990 + ... + 45209.

It is an arithmetic number, because the mean of its divisors is an integer number (1217700).

Almost surely, 2^9921890 is an apocalyptic number.

9921890 is a deficient number, since it is larger than the sum of its proper divisors (9561310).

9921890 is a wasteful number, since it uses less digits than its factorization.

9921890 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 90217.

The product of its (nonzero) digits is 11664, while the sum is 38.

The square root of 9921890 is about 3149.9031731150. The cubic root of 9921890 is about 214.8810591449.

It can be divided in two parts, 992 and 1890, that added together give a palindrome (2882).

The spelling of 9921890 in words is "nine million, nine hundred twenty-one thousand, eight hundred ninety".