121205720 has 16 divisors (see below), whose sum is σ = 272712960. Its totient is φ = 48482272.

The previous prime is 121205683. The next prime is 121205723. The reversal of 121205720 is 27502121.

It is a Harshad number since it is a multiple of its sum of digits (20).

It is a junction number, because it is equal to n+sod(n) for n = 121205692 and 121205701.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (121205723) 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, 1515032 + ... + 1515111.

It is an arithmetic number, because the mean of its divisors is an integer number (17044560).

Almost surely, 2^121205720 is an apocalyptic number.

121205720 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

121205720 is an abundant number, since it is smaller than the sum of its proper divisors (151507240).

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

121205720 is a wasteful number, since it uses less digits than its factorization.

121205720 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3030154 (or 3030150 counting only the distinct ones).

The product of its (nonzero) digits is 280, while the sum is 20.

The square root of 121205720 is about 11009.3469379432. The cubic root of 121205720 is about 494.8888911591. Note that the first 4 decimals are identical.

Adding to 121205720 its reverse (27502121), we get a palindrome (148707841).

The spelling of 121205720 in words is "one hundred twenty-one million, two hundred five thousand, seven hundred twenty".