121291781 has 16 divisors (see below), whose sum is σ = 133862400. Its totient is φ = 109219968.

The previous prime is 121291771. The next prime is 121291799. The reversal of 121291781 is 187192121.

It is not a de Polignac number, because 121291781 - 2¹⁴ = 121275397 is a prime.

It is a super-2 number, since 2×121291781² = 29423392276303922, which contains 22 as substring.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (121291771) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 90740 + ... + 92066.

It is an arithmetic number, because the mean of its divisors is an integer number (8366400).

Almost surely, 2^121291781 is an apocalyptic number.

It is an amenable number.

121291781 is a deficient number, since it is larger than the sum of its proper divisors (12570619).

121291781 is a wasteful number, since it uses less digits than its factorization.

121291781 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1508.

The product of its digits is 2016, while the sum is 32.

The square root of 121291781 is about 11013.2547868466. The cubic root of 121291781 is about 495.0059938736.

The spelling of 121291781 in words is "one hundred twenty-one million, two hundred ninety-one thousand, seven hundred eighty-one".