121566639 has 4 divisors (see below), whose sum is σ = 162088856. Its totient is φ = 81044424.

The previous prime is 121566631. The next prime is 121566649. The reversal of 121566639 is 936665121.

It is a semiprime because it is the product of two primes.

It is not a de Polignac number, because 121566639 - 2³ = 121566631 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 121566597 and 121566606.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (121566631) 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, 20261104 + ... + 20261109.

It is an arithmetic number, because the mean of its divisors is an integer number (40522214).

Almost surely, 2^121566639 is an apocalyptic number.

121566639 is a deficient number, since it is larger than the sum of its proper divisors (40522217).

121566639 is an equidigital number, since it uses as much as digits as its factorization.

121566639 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 40522216.

The product of its digits is 58320, while the sum is 39.

The square root of 121566639 is about 11025.7262345843. The cubic root of 121566639 is about 495.3796210438.

It can be divided in two parts, 12 and 1566639, that added together give a palindrome (1566651).

The spelling of 121566639 in words is "one hundred twenty-one million, five hundred sixty-six thousand, six hundred thirty-nine".