121664809 has 16 divisors (see below), whose sum is σ = 147502080. Its totient is φ = 98027280.

The previous prime is 121664783. The next prime is 121664827. The reversal of 121664809 is 908466121.

It is a happy number.

It is a cyclic number.

It is not a de Polignac number, because 121664809 - 2¹⁵ = 121632041 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (121664849) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 13932 + ... + 20914.

It is an arithmetic number, because the mean of its divisors is an integer number (9218880).

Almost surely, 2^121664809 is an apocalyptic number.

121664809 is a gapful number since it is divisible by the number (19) formed by its first and last digit.

It is an amenable number.

121664809 is a deficient number, since it is larger than the sum of its proper divisors (25837271).

121664809 is a wasteful number, since it uses less digits than its factorization.

121664809 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7140.

The product of its (nonzero) digits is 20736, while the sum is 37.

The square root of 121664809 is about 11030.1771971261. The cubic root of 121664809 is about 495.5129315558.

The spelling of 121664809 in words is "one hundred twenty-one million, six hundred sixty-four thousand, eight hundred nine".