121655720 has 16 divisors (see below), whose sum is σ = 273725460. Its totient is φ = 48662272.

The previous prime is 121655657. The next prime is 121655753. The reversal of 121655720 is 27556121.

It can be written as a sum of positive squares in 2 ways, for example, as 100440484 + 21215236 = 10022^2 + 4606^2 .

It is a super-2 number, since 2×121655720² = 29600228417436800, which contains 22 as substring.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1520657 + ... + 1520736.

Almost surely, 2^121655720 is an apocalyptic number.

121655720 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

121655720 is an abundant number, since it is smaller than the sum of its proper divisors (152069740).

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

121655720 is a wasteful number, since it uses less digits than its factorization.

121655720 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3041404 (or 3041400 counting only the distinct ones).

The product of its (nonzero) digits is 4200, while the sum is 29.

The square root of 121655720 is about 11029.7651833573. The cubic root of 121655720 is about 495.5005921093.

The spelling of 121655720 in words is "one hundred twenty-one million, six hundred fifty-five thousand, seven hundred twenty".