1321216621 has 8 divisors (see below), whose sum is σ = 1367967488. Its totient is φ = 1274724000.

The previous prime is 1321216607. The next prime is 1321216639. The reversal of 1321216621 is 1266121231.

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 a de Polignac number, because none of the positive numbers 2^k-1321216621 is a prime.

It is a super-2 number, since 2×1321216621² = 3491226719213315282, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1321216601) 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, 54120 + ... + 74641.

It is an arithmetic number, because the mean of its divisors is an integer number (170995936).

Almost surely, 2^1321216621 is an apocalyptic number.

It is an amenable number.

1321216621 is a deficient number, since it is larger than the sum of its proper divisors (46750867).

1321216621 is a wasteful number, since it uses less digits than its factorization.

1321216621 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 129123.

The product of its digits is 864, while the sum is 25.

The square root of 1321216621 is about 36348.5435884301. The cubic root of 1321216621 is about 1097.2982237074.

Adding to 1321216621 its reverse (1266121231), we get a palindrome (2587337852).

The spelling of 1321216621 in words is "one billion, three hundred twenty-one million, two hundred sixteen thousand, six hundred twenty-one".