121777656 has 256 divisors, whose sum is σ = 422876160. Its totient is φ = 28200960.

The previous prime is 121777639. The next prime is 121777657. The reversal of 121777656 is 656777121.

It is a Harshad number since it is a multiple of its sum of digits (42).

Its product of digits (123480) is a multiple of the sum of its prime divisors (210).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (121777657) by changing a digit.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 888820 + ... + 888956.

It is an arithmetic number, because the mean of its divisors is an integer number (1651860).

Almost surely, 2^121777656 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 121777656, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (211438080).

121777656 is an abundant number, since it is smaller than the sum of its proper divisors (301098504).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

121777656 is a wasteful number, since it uses less digits than its factorization.

121777656 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 214 (or 210 counting only the distinct ones).

The product of its digits is 123480, while the sum is 42.

The square root of 121777656 is about 11035.2913871814. The cubic root of 121777656 is about 495.6660842189. Note that the first 3 decimals are identical.

It can be divided in two parts, 121 and 777656, that added together give a palindrome (777777).

The spelling of 121777656 in words is "one hundred twenty-one million, seven hundred seventy-seven thousand, six hundred fifty-six".