1221555500010 has 48 divisors (see below), whose sum is σ = 3176174646216. Its totient is φ = 325734764544.

The previous prime is 1221555499979. The next prime is 1221555500017. The reversal of 1221555500010 is 100055551221.

1221555500010 is a `hidden beast` number, since 1 + 2 + 2 + 155 + 5 + 500 + 0 + 1 + 0 = 666.

It can be written as a sum of positive squares in 4 ways, for example, as 1171349479521 + 50206020489 = 1082289^2 + 224067^2 .

It is a super-2 number, since 2×1221555500010² (a number of 25 digits) contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (1221555500017) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 2032582 + ... + 2564078.

Almost surely, 2^{1221555500010} is an apocalyptic number.

1221555500010 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

1221555500010 is an abundant number, since it is smaller than the sum of its proper divisors (1954619146206).

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

1221555500010 is a wasteful number, since it uses less digits than its factorization.

1221555500010 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 557047 (or 557044 counting only the distinct ones).

The product of its (nonzero) digits is 2500, while the sum is 27.

The spelling of 1221555500010 in words is "one trillion, two hundred twenty-one billion, five hundred fifty-five million, five hundred thousand, ten".