101221890 has 128 divisors (see below), whose sum is σ = 313528320. Its totient is φ = 20294400.

The previous prime is 101221877. The next prime is 101221909. The reversal of 101221890 is 98122101.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 101221890.

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 63 ways as a sum of consecutive naturals, for example, 66235 + ... + 67745.

It is an arithmetic number, because the mean of its divisors is an integer number (2449440).

Almost surely, 2^101221890 is an apocalyptic number.

101221890 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is a practical number, because each smaller number is the sum of distinct divisors of 101221890, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (156764160).

101221890 is an abundant number, since it is smaller than the sum of its proper divisors (212306430).

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

101221890 is a wasteful number, since it uses less digits than its factorization.

101221890 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1568.

The product of its (nonzero) digits is 288, while the sum is 24.

The square root of 101221890 is about 10060.9090046576. The cubic root of 101221890 is about 466.0417389103.

Adding to 101221890 its reverse (98122101), we get a palindrome (199343991).

The spelling of 101221890 in words is "one hundred one million, two hundred twenty-one thousand, eight hundred ninety".