1216553920 has 28 divisors (see below), whose sum is σ = 2896919784. Its totient is φ = 486621440.

The previous prime is 1216553911. The next prime is 1216553929. The reversal of 1216553920 is 293556121.

It is an interprime number because it is at equal distance from previous prime (1216553911) and next prime (1216553929).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1216553929) 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, 1900546 + ... + 1901185.

Almost surely, 2^1216553920 is an apocalyptic number.

1216553920 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

1216553920 is an abundant number, since it is smaller than the sum of its proper divisors (1680365864).

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

1216553920 is an equidigital number, since it uses as much as digits as its factorization.

1216553920 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3801748 (or 3801738 counting only the distinct ones).

The product of its (nonzero) digits is 16200, while the sum is 34.

The square root of 1216553920 is about 34879.1330167480. The cubic root of 1216553920 is about 1067.5227051755.

The spelling of 1216553920 in words is "one billion, two hundred sixteen million, five hundred fifty-three thousand, nine hundred twenty".