1216421525 has 12 divisors (see below), whose sum is σ = 1645486944. Its totient is φ = 884670000.

The previous prime is 1216421513. The next prime is 1216421527. The reversal of 1216421525 is 5251246121.

It is not a de Polignac number, because 1216421525 - 2¹² = 1216417429 is a prime.

It is a hoax number, since the sum of its digits (29) coincides with the sum of the digits of its distinct prime factors.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1216421527) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 2211401 + ... + 2211950.

It is an arithmetic number, because the mean of its divisors is an integer number (137123912).

Almost surely, 2^1216421525 is an apocalyptic number.

It is an amenable number.

1216421525 is a deficient number, since it is larger than the sum of its proper divisors (429065419).

1216421525 is a wasteful number, since it uses less digits than its factorization.

1216421525 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4423372 (or 4423367 counting only the distinct ones).

The product of its digits is 4800, while the sum is 29.

The square root of 1216421525 is about 34877.2350538284. The cubic root of 1216421525 is about 1067.4839783550.

Adding to 1216421525 its reverse (5251246121), we get a palindrome (6467667646).

The spelling of 1216421525 in words is "one billion, two hundred sixteen million, four hundred twenty-one thousand, five hundred twenty-five".