1216621501 has 8 divisors (see below), whose sum is σ = 1269903744. Its totient is φ = 1163371440.

The previous prime is 1216621499. The next prime is 1216621517. The reversal of 1216621501 is 1051266121.

It is a happy number.

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 1216621501 - 2¹ = 1216621499 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 (1216621001) 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, 100560 + ... + 112006.

It is an arithmetic number, because the mean of its divisors is an integer number (158737968).

Almost surely, 2^1216621501 is an apocalyptic number.

It is an amenable number.

1216621501 is a deficient number, since it is larger than the sum of its proper divisors (53282243).

1216621501 is a wasteful number, since it uses less digits than its factorization.

1216621501 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 16091.

The product of its (nonzero) digits is 720, while the sum is 25.

The square root of 1216621501 is about 34880.1017917093. The cubic root of 1216621501 is about 1067.5424721898.

Adding to 1216621501 its reverse (1051266121), we get a palindrome (2267887622).

The spelling of 1216621501 in words is "one billion, two hundred sixteen million, six hundred twenty-one thousand, five hundred one".