221121001000 has 64 divisors (see below), whose sum is σ = 519437065680. Its totient is φ = 88104140800.

The previous prime is 221121000973. The next prime is 221121001021. The reversal of 221121001000 is 100121122.

It can be written as a sum of positive squares in 8 ways, for example, as 114559233156 + 106561767844 = 338466^2 + 326438^2 .

It is a Harshad number since it is a multiple of its sum of digits (10).

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 173197 + ... + 687196.

Almost surely, 2^221121001000 is an apocalyptic number.

221121001000 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

221121001000 is an abundant number, since it is smaller than the sum of its proper divisors (298316064680).

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

221121001000 is a wasteful number, since it uses less digits than its factorization.

221121001000 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 860671 (or 860657 counting only the distinct ones).

The product of its (nonzero) digits is 8, while the sum is 10.

Adding to 221121001000 its reverse (100121122), we get a palindrome (221221122122).

The spelling of 221121001000 in words is "two hundred twenty-one billion, one hundred twenty-one million, one thousand".