209421890 has 16 divisors (see below), whose sum is σ = 381732480. Its totient is φ = 82708080.

The previous prime is 209421881. The next prime is 209421907. The reversal of 209421890 is 98124902.

It is a super-2 number, since 2×209421890² = 87715056022344200, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 209421890.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 131756 + ... + 133335.

It is an arithmetic number, because the mean of its divisors is an integer number (23858280).

Almost surely, 2^209421890 is an apocalyptic number.

209421890 is a deficient number, since it is larger than the sum of its proper divisors (172310590).

209421890 is a wasteful number, since it uses less digits than its factorization.

209421890 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 265177.

The product of its (nonzero) digits is 10368, while the sum is 35.

The square root of 209421890 is about 14471.4163094011. The cubic root of 209421890 is about 593.8462589643.

The spelling of 209421890 in words is "two hundred nine million, four hundred twenty-one thousand, eight hundred ninety".