121720781 has 8 divisors (see below), whose sum is σ = 149810304. Its totient is φ = 96306480.

The previous prime is 121720769. The next prime is 121720793. The reversal of 121720781 is 187027121.

It is an interprime number because it is at equal distance from previous prime (121720769) and next prime (121720793).

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 121720781 - 2²² = 117526477 is a prime.

It is a super-2 number, since 2×121720781² = 29631897054499922, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (121723781) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 668705 + ... + 668886.

It is an arithmetic number, because the mean of its divisors is an integer number (18726288).

Almost surely, 2^121720781 is an apocalyptic number.

It is an amenable number.

121720781 is a deficient number, since it is larger than the sum of its proper divisors (28089523).

121720781 is a wasteful number, since it uses less digits than its factorization.

121720781 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1337611.

The product of its (nonzero) digits is 1568, while the sum is 29.

The square root of 121720781 is about 11032.7141266327. The cubic root of 121720781 is about 495.5889069562.

The spelling of 121720781 in words is "one hundred twenty-one million, seven hundred twenty thousand, seven hundred eighty-one".