1221451503555 has 64 divisors (see below), whose sum is σ = 2038088687616. Its totient is φ = 623980800000.

The previous prime is 1221451503551. The next prime is 1221451503653. The reversal of 1221451503555 is 5553051541221.

It is not a de Polignac number, because 1221451503555 - 2² = 1221451503551 is a prime.

It is not an unprimeable number, because it can be changed into a prime (1221451503551) by changing a digit.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 19418155 + ... + 19480955.

It is an arithmetic number, because the mean of its divisors is an integer number (31845135744).

Almost surely, 2^{1221451503555} is an apocalyptic number.

1221451503555 is a gapful number since it is divisible by the number (15) formed by its first and last digit.

1221451503555 is a deficient number, since it is larger than the sum of its proper divisors (816637184061).

1221451503555 is a wasteful number, since it uses less digits than its factorization.

1221451503555 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 63268.

The product of its (nonzero) digits is 150000, while the sum is 39.

The spelling of 1221451503555 in words is "one trillion, two hundred twenty-one billion, four hundred fifty-one million, five hundred three thousand, five hundred fifty-five".