1221978599 has 2 divisors, whose sum is σ = 1221978600. Its totient is φ = 1221978598.

The previous prime is 1221978587. The next prime is 1221978631. The reversal of 1221978599 is 9958791221.

It is a happy number.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 1221978599 - 2¹² = 1221974503 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 1221978599.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1221978529) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 610989299 + 610989300.

It is an arithmetic number, because the mean of its divisors is an integer number (610989300).

Almost surely, 2^1221978599 is an apocalyptic number.

1221978599 is a deficient number, since it is larger than the sum of its proper divisors (1).

1221978599 is an equidigital number, since it uses as much as digits as its factorization.

1221978599 is an evil number, because the sum of its binary digits is even.

The product of its digits is 816480, while the sum is 53.

The square root of 1221978599 is about 34956.8104809349. The cubic root of 1221978599 is about 1069.1070662009.

The spelling of 1221978599 in words is "one billion, two hundred twenty-one million, nine hundred seventy-eight thousand, five hundred ninety-nine".