1213977221 has 4 divisors (see below), whose sum is σ = 1232096352. Its totient is φ = 1195858092.

The previous prime is 1213977217. The next prime is 1213977227. The reversal of 1213977221 is 1227793121.

It is a happy number.

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.

It is a cyclic number.

It is not a de Polignac number, because 1213977221 - 2² = 1213977217 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 (1213977227) 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, 9059465 + ... + 9059598.

It is an arithmetic number, because the mean of its divisors is an integer number (308024088).

Almost surely, 2^1213977221 is an apocalyptic number.

It is an amenable number.

1213977221 is a deficient number, since it is larger than the sum of its proper divisors (18119131).

1213977221 is an equidigital number, since it uses as much as digits as its factorization.

1213977221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 18119130.

The product of its digits is 10584, while the sum is 35.

The square root of 1213977221 is about 34842.1758935920. The cubic root of 1213977221 is about 1066.7684903556.

The spelling of 1213977221 in words is "one billion, two hundred thirteen million, nine hundred seventy-seven thousand, two hundred twenty-one".