1221315100 has 36 divisors (see below), whose sum is σ = 2652146224. Its totient is φ = 488177280.

The previous prime is 1221315059. The next prime is 1221315103. The reversal of 1221315100 is 15131221.

It is a super-2 number, since 2×1221315100² = 2983221146976020000, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1221315103) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 171817 + ... + 178783.

Almost surely, 2^1221315100 is an apocalyptic number.

1221315100 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

1221315100 is an abundant number, since it is smaller than the sum of its proper divisors (1430831124).

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

1221315100 is a wasteful number, since it uses less digits than its factorization.

1221315100 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8734 (or 8727 counting only the distinct ones).

The product of its (nonzero) digits is 60, while the sum is 16.

The square root of 1221315100 is about 34947.3189243467. The cubic root of 1221315100 is about 1068.9135331078.

Adding to 1221315100 its reverse (15131221), we get a palindrome (1236446321).

The spelling of 1221315100 in words is "one billion, two hundred twenty-one million, three hundred fifteen thousand, one hundred".