1221255512064 has 600 divisors, whose sum is σ = 4194702369088. Its totient is φ = 348285173760.

The previous prime is 1221255512051. The next prime is 1221255512077. The reversal of 1221255512064 is 4602155521221.

1221255512064 is a `hidden beast` number, since 1 + 2 + 2 + 1 + 25 + 551 + 20 + 64 = 666.

It is an interprime number because it is at equal distance from previous prime (1221255512051) and next prime (1221255512077).

It is a Harshad number since it is a multiple of its sum of digits (36).

It is an unprimeable number.

It is a polite number, since it can be written in 39 ways as a sum of consecutive naturals, for example, 2257403634 + ... + 2257404174.

Almost surely, 2^{1221255512064} is an apocalyptic number.

1221255512064 is a gapful number since it is divisible by the number (14) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 1221255512064, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2097351184544).

1221255512064 is an abundant number, since it is smaller than the sum of its proper divisors (2973446857024).

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

1221255512064 is an frugal number, since it uses more digits than its factorization.

1221255512064 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 603 (or 553 counting only the distinct ones).

The product of its (nonzero) digits is 48000, while the sum is 36.

The spelling of 1221255512064 in words is "one trillion, two hundred twenty-one billion, two hundred fifty-five million, five hundred twelve thousand, sixty-four".