1221006554 has 4 divisors (see below), whose sum is σ = 1831509834. Its totient is φ = 610503276.

The previous prime is 1221006551. The next prime is 1221006581. The reversal of 1221006554 is 4556001221.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in only one way, i.e., 1214871025 + 6135529 = 34855^2 + 2477^2 .

It is not an unprimeable number, because it can be changed into a prime (1221006551) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 305251637 + ... + 305251640.

Almost surely, 2^1221006554 is an apocalyptic number.

1221006554 is a deficient number, since it is larger than the sum of its proper divisors (610503280).

1221006554 is an equidigital number, since it uses as much as digits as its factorization.

1221006554 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 610503279.

The product of its (nonzero) digits is 2400, while the sum is 26.

The square root of 1221006554 is about 34942.9042009962. The cubic root of 1221006554 is about 1068.8235108107.

Adding to 1221006554 its reverse (4556001221), we get a palindrome (5777007775).

The spelling of 1221006554 in words is "one billion, two hundred twenty-one million, six thousand, five hundred fifty-four".