1215520122400 has 144 divisors (see below), whose sum is σ = 3051207975816. Its totient is φ = 472505425920.

The previous prime is 1215520122371. The next prime is 1215520122403. The reversal of 1215520122400 is 42210255121.

It can be written as a sum of positive squares in 12 ways, for example, as 293144279184 + 922375843216 = 541428^2 + 960404^2 .

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

It is not an unprimeable number, because it can be changed into a prime (1215520122403) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 25343242 + ... + 25391158.

Almost surely, 2^{1215520122400} is an apocalyptic number.

1215520122400 is a gapful number since it is divisible by the number (10) 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 1215520122400, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1525603987908).

1215520122400 is an abundant number, since it is smaller than the sum of its proper divisors (1835687853416).

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

1215520122400 is a wasteful number, since it uses less digits than its factorization.

1215520122400 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 48831 (or 48818 counting only the distinct ones).

The product of its (nonzero) digits is 1600, while the sum is 25.

Adding to 1215520122400 its reverse (42210255121), we get a palindrome (1257730377521).

The spelling of 1215520122400 in words is "one trillion, two hundred fifteen billion, five hundred twenty million, one hundred twenty-two thousand, four hundred".