1216356501 has 4 divisors (see below), whose sum is σ = 1621808672. Its totient is φ = 810904332.

The previous prime is 1216356487. The next prime is 1216356509. The reversal of 1216356501 is 1056536121.

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: 1056536121 = 3 ⋅352178707.

It is not a de Polignac number, because 1216356501 - 2²⁵ = 1182802069 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1216356509) 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, 202726081 + ... + 202726086.

It is an arithmetic number, because the mean of its divisors is an integer number (405452168).

Almost surely, 2^1216356501 is an apocalyptic number.

It is an amenable number.

1216356501 is a deficient number, since it is larger than the sum of its proper divisors (405452171).

1216356501 is an equidigital number, since it uses as much as digits as its factorization.

1216356501 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 405452170.

The product of its (nonzero) digits is 5400, while the sum is 30.

The square root of 1216356501 is about 34876.3028573844. The cubic root of 1216356501 is about 1067.4649571759.

The spelling of 1216356501 in words is "one billion, two hundred sixteen million, three hundred fifty-six thousand, five hundred one".