1221426636 has 12 divisors (see below), whose sum is σ = 2849995512. Its totient is φ = 407142208.

The previous prime is 1221426617. The next prime is 1221426637. The reversal of 1221426636 is 6366241221.

It is a tau number, because it is divible by the number of its divisors (12).

It is a nude number because it is divisible by every one of its digits.

It is a junction number, because it is equal to n+sod(n) for n = 1221426597 and 1221426606.

It is not an unprimeable number, because it can be changed into a prime (1221426637) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 50892765 + ... + 50892788.

It is an arithmetic number, because the mean of its divisors is an integer number (237499626).

Almost surely, 2^1221426636 is an apocalyptic number.

It is an amenable number.

1221426636 is an abundant number, since it is smaller than the sum of its proper divisors (1628568876).

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

1221426636 is a wasteful number, since it uses less digits than its factorization.

1221426636 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 101785560 (or 101785558 counting only the distinct ones).

The product of its digits is 20736, while the sum is 33.

The square root of 1221426636 is about 34948.9146612595. The cubic root of 1221426636 is about 1068.9460714513.

Adding to 1221426636 its reverse (6366241221), we get a palindrome (7587667857).

It can be divided in two parts, 122142 and 6636, that added together give a triangular number (128778 = T₅₀₇).

The spelling of 1221426636 in words is "one billion, two hundred twenty-one million, four hundred twenty-six thousand, six hundred thirty-six".