121665990 has 32 divisors (see below), whose sum is σ = 299892960. Its totient is φ = 31567104.

The previous prime is 121665977. The next prime is 121666003. The reversal of 121665990 is 99566121.

It is an interprime number because it is at equal distance from previous prime (121665977) and next prime (121666003).

It is a super-2 number, since 2×121665990² = 29605226245360200, which contains 22 as substring.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 53695 + ... + 55914.

It is an arithmetic number, because the mean of its divisors is an integer number (9371655).

Almost surely, 2^121665990 is an apocalyptic number.

121665990 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

121665990 is an abundant number, since it is smaller than the sum of its proper divisors (178226970).

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

121665990 is a wasteful number, since it uses less digits than its factorization.

121665990 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 109656.

The product of its (nonzero) digits is 29160, while the sum is 39.

The square root of 121665990 is about 11030.2307319475. The cubic root of 121665990 is about 495.5145348649.

The spelling of 121665990 in words is "one hundred twenty-one million, six hundred sixty-five thousand, nine hundred ninety".