122640021 has 16 divisors (see below), whose sum is σ = 207644800. Its totient is φ = 70079904.

The previous prime is 122640019. The next prime is 122640103. The reversal of 122640021 is 120046221.

122640021 is a `hidden beast` number, since 1 + 2 + 2 + 640 + 0 + 21 = 666.

It is not a de Polignac number, because 122640021 - 2¹ = 122640019 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 122639976 and 122640003.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (122640121) 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, 324256 + ... + 324633.

It is an arithmetic number, because the mean of its divisors is an integer number (12977800).

Almost surely, 2^122640021 is an apocalyptic number.

It is an amenable number.

122640021 is a deficient number, since it is larger than the sum of its proper divisors (85004779).

122640021 is an equidigital number, since it uses as much as digits as its factorization.

122640021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 648905 (or 648899 counting only the distinct ones).

The product of its (nonzero) digits is 192, while the sum is 18.

The square root of 122640021 is about 11074.2955080673. The cubic root of 122640021 is about 496.8333483063.

Adding to 122640021 its reverse (120046221), we get a palindrome (242686242).

The spelling of 122640021 in words is "one hundred twenty-two million, six hundred forty thousand, twenty-one".