1225916198521 has 27 divisors (see below), whose sum is σ = 1450386504333. Its totient is φ = 1033160728320.

The previous prime is 1225916198489. The next prime is 1225916198539. The reversal of 1225916198521 is 1258916195221.

The square root of 1225916198521 is 1107211.

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

It can be written as a sum of positive squares in 4 ways, for example, as 281202181225 + 944714017296 = 530285^2 + 971964^2 .

It is not a de Polignac number, because 1225916198521 - 2⁵ = 1225916198489 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1225916198821) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 26 ways as a sum of consecutive naturals, for example, 472777801 + ... + 472780393.

It is an arithmetic number, because the mean of its divisors is an integer number (53718018679).

Almost surely, 2^{1225916198521} is an apocalyptic number.

1225916198521 is the 1107211-st square number.

1225916198521 is the 553606-th centered octagonal number.

It is an amenable number.

1225916198521 is a deficient number, since it is larger than the sum of its proper divisors (224470305812).

1225916198521 is an frugal number, since it uses more digits than its factorization.

1225916198521 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5322 (or 2661 counting only the distinct ones).

The product of its digits is 777600, while the sum is 52.

The spelling of 1225916198521 in words is "one trillion, two hundred twenty-five billion, nine hundred sixteen million, one hundred ninety-eight thousand, five hundred twenty-one".