1221921923 has 2 divisors, whose sum is σ = 1221921924. Its totient is φ = 1221921922.

The previous prime is 1221921913. The next prime is 1221921949. The reversal of 1221921923 is 3291291221.

It is a happy number.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 1221921923 - 2⁴ = 1221921907 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 1221921923.

It is not a weakly prime, because it can be changed into another prime (1221921913) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 610960961 + 610960962.

It is an arithmetic number, because the mean of its divisors is an integer number (610960962).

Almost surely, 2^1221921923 is an apocalyptic number.

1221921923 is a deficient number, since it is larger than the sum of its proper divisors (1).

1221921923 is an equidigital number, since it uses as much as digits as its factorization.

1221921923 is an evil number, because the sum of its binary digits is even.

The product of its digits is 3888, while the sum is 32.

The square root of 1221921923 is about 34955.9998140520. Note that the first 3 decimals coincide. The cubic root of 1221921923 is about 1069.0905373656.

The spelling of 1221921923 in words is "one billion, two hundred twenty-one million, nine hundred twenty-one thousand, nine hundred twenty-three".