1555220997225 has 405 divisors, whose sum is σ = 3476651271093. Its totient is φ = 685278195840.

The previous prime is 1555220997199. The next prime is 1555220997251. The reversal of 1555220997225 is 5227990225551.

The square root of 1555220997225 is 1247085.

It is a perfect power (a square), and thus also a powerful number.

1555220997225 is a `hidden beast` number, since 1 + 5 + 5 + 522 + 0 + 9 + 97 + 2 + 25 = 666.

It is an interprime number because it is at equal distance from previous prime (1555220997199) and next prime (1555220997251).

It can be written as a sum of positive squares in 4 ways, for example, as 147638072169 + 1407582925056 = 384237^2 + 1186416^2 .

It is a tau number, because it is divible by the number of its divisors (405).

It is not a de Polignac number, because 1555220997225 - 2²⁵ = 1555187442793 is a prime.

It is an unprimeable number.

It is a polite number, since it can be written in 404 ways as a sum of consecutive naturals, for example, 14534775622 + ... + 14534775728.

Almost surely, 2^{1555220997225} is an apocalyptic number.

1555220997225 is a gapful number since it is divisible by the number (15) formed by its first and last digit.

1555220997225 is the 1247085-th square number.

1555220997225 is the 623543-rd centered octagonal number.

It is an amenable number.

1555220997225 is an abundant number, since it is smaller than the sum of its proper divisors (1921430273868).

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

1555220997225 is an equidigital number, since it uses as much as digits as its factorization.

1555220997225 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 324 (or 159 counting only the distinct ones).

The product of its (nonzero) digits is 5670000, while the sum is 54.

The spelling of 1555220997225 in words is "one trillion, five hundred fifty-five billion, two hundred twenty million, nine hundred ninety-seven thousand, two hundred twenty-five".