1221054550 has 12 divisors (see below), whose sum is σ = 2271161556. Its totient is φ = 488421800.

The previous prime is 1221054539. The next prime is 1221054557. The reversal of 1221054550 is 554501221.

It is a Harshad number since it is a multiple of its sum of digits (25).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1221054557) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 12210496 + ... + 12210595.

It is an arithmetic number, because the mean of its divisors is an integer number (189263463).

Almost surely, 2^1221054550 is an apocalyptic number.

1221054550 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

1221054550 is a deficient number, since it is larger than the sum of its proper divisors (1050107006).

1221054550 is a wasteful number, since it uses less digits than its factorization.

1221054550 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 24421103 (or 24421098 counting only the distinct ones).

The product of its (nonzero) digits is 2000, while the sum is 25.

The square root of 1221054550 is about 34943.5909717361. The cubic root of 1221054550 is about 1068.8375152621.

Adding to 1221054550 its reverse (554501221), we get a palindrome (1775555771).

The spelling of 1221054550 in words is "one billion, two hundred twenty-one million, fifty-four thousand, five hundred fifty".