121820791990 has 16 divisors (see below), whose sum is σ = 219482568720. Its totient is φ = 48682729440.

The previous prime is 121820791987. The next prime is 121820791991. The reversal of 121820791990 is 99197028121.

It is a happy number.

It is a super-2 number, since 2×121820791990² (a number of 23 digits) contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (121820791991) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 5687196 + ... + 5708575.

It is an arithmetic number, because the mean of its divisors is an integer number (13717660545).

Almost surely, 2^121820791990 is an apocalyptic number.

121820791990 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

121820791990 is a deficient number, since it is larger than the sum of its proper divisors (97661776730).

121820791990 is a wasteful number, since it uses less digits than its factorization.

121820791990 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 11396847.

The product of its (nonzero) digits is 163296, while the sum is 49.

The spelling of 121820791990 in words is "one hundred twenty-one billion, eight hundred twenty million, seven hundred ninety-one thousand, nine hundred ninety".