121665978 has 24 divisors (see below), whose sum is σ = 301268448. Its totient is φ = 34761672.

The previous prime is 121665977. The next prime is 121666003. The reversal of 121665978 is 879566121.

It is a super-2 number, since 2×121665978² = 29605220405392968, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (121665977) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 482676 + ... + 482927.

It is an arithmetic number, because the mean of its divisors is an integer number (12552852).

Almost surely, 2^121665978 is an apocalyptic number.

121665978 is a gapful number since it is divisible by the number (18) formed by its first and last digit.

121665978 is an abundant number, since it is smaller than the sum of its proper divisors (179602470).

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

121665978 is a wasteful number, since it uses less digits than its factorization.

121665978 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 965618 (or 965615 counting only the distinct ones).

The product of its digits is 181440, while the sum is 45.

The square root of 121665978 is about 11030.2301879879. The cubic root of 121665978 is about 495.5145185739.

The spelling of 121665978 in words is "one hundred twenty-one million, six hundred sixty-five thousand, nine hundred seventy-eight".