1209821147 has 4 divisors (see below), whose sum is σ = 1209914496. Its totient is φ = 1209727800.

The previous prime is 1209821131. The next prime is 1209821149. The reversal of 1209821147 is 7411289021.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length, and also an emirpimes, since its reverse is a distinct semiprime: 7411289021 = 16007 ⋅463003.

It is a cyclic number.

It is not a de Polignac number, because 1209821147 - 2⁴ = 1209821131 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1209821149) 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, 23348 + ... + 54449.

It is an arithmetic number, because the mean of its divisors is an integer number (302478624).

Almost surely, 2^1209821147 is an apocalyptic number.

1209821147 is a deficient number, since it is larger than the sum of its proper divisors (93349).

1209821147 is an equidigital number, since it uses as much as digits as its factorization.

1209821147 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 93348.

The product of its (nonzero) digits is 8064, while the sum is 35.

The square root of 1209821147 is about 34782.4833357252. The cubic root of 1209821147 is about 1065.5497311060.

The spelling of 1209821147 in words is "one billion, two hundred nine million, eight hundred twenty-one thousand, one hundred forty-seven".