1216551405 has 8 divisors (see below), whose sum is σ = 1946482272. Its totient is φ = 648827408.

The previous prime is 1216551403. The next prime is 1216551409. The reversal of 1216551405 is 5041556121.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 1216551405 - 2¹ = 1216551403 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1216551403) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 40551699 + ... + 40551728.

It is an arithmetic number, because the mean of its divisors is an integer number (243310284).

Almost surely, 2^1216551405 is an apocalyptic number.

1216551405 is a gapful number since it is divisible by the number (15) formed by its first and last digit.

It is an amenable number.

1216551405 is a deficient number, since it is larger than the sum of its proper divisors (729930867).

1216551405 is an equidigital number, since it uses as much as digits as its factorization.

1216551405 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 81103435.

The product of its (nonzero) digits is 6000, while the sum is 30.

The square root of 1216551405 is about 34879.0969636543. The cubic root of 1216551405 is about 1067.5219695398.

The spelling of 1216551405 in words is "one billion, two hundred sixteen million, five hundred fifty-one thousand, four hundred five".