1221154399 has 2 divisors, whose sum is σ = 1221154400. Its totient is φ = 1221154398.

The previous prime is 1221154393. The next prime is 1221154409. The reversal of 1221154399 is 9934511221.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 1221154399 - 2⁵ = 1221154367 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1221154393) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 610577199 + 610577200.

It is an arithmetic number, because the mean of its divisors is an integer number (610577200).

Almost surely, 2^1221154399 is an apocalyptic number.

1221154399 is a deficient number, since it is larger than the sum of its proper divisors (1).

1221154399 is an equidigital number, since it uses as much as digits as its factorization.

1221154399 is an evil number, because the sum of its binary digits is even.

The product of its digits is 19440, while the sum is 37.

The square root of 1221154399 is about 34945.0196594593. The cubic root of 1221154399 is about 1068.8666483990.

The spelling of 1221154399 in words is "one billion, two hundred twenty-one million, one hundred fifty-four thousand, three hundred ninety-nine".