1225210521 has 4 divisors (see below), whose sum is σ = 1633614032. Its totient is φ = 816807012.

The previous prime is 1225210507. The next prime is 1225210537. The reversal of 1225210521 is 1250125221.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 1250125221 = 3 ⋅416708407.

It is not a de Polignac number, because 1225210521 - 2⁶ = 1225210457 is a prime.

It is a super-2 number, since 2×1225210521² = 3002281641538182882, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1225210541) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 204201751 + ... + 204201756.

It is an arithmetic number, because the mean of its divisors is an integer number (408403508).

Almost surely, 2^1225210521 is an apocalyptic number.

It is an amenable number.

1225210521 is a deficient number, since it is larger than the sum of its proper divisors (408403511).

1225210521 is an equidigital number, since it uses as much as digits as its factorization.

1225210521 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 408403510.

The product of its (nonzero) digits is 400, while the sum is 21.

The square root of 1225210521 is about 35003.0073136581. The cubic root of 1225210521 is about 1070.0487708867.

Adding to 1225210521 its reverse (1250125221), we get a palindrome (2475335742).

The spelling of 1225210521 in words is "one billion, two hundred twenty-five million, two hundred ten thousand, five hundred twenty-one".