78921398 has 4 divisors (see below), whose sum is σ = 118382100. Its totient is φ = 39460698.

The previous prime is 78921397. The next prime is 78921439. The reversal of 78921398 is 89312987.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 89312987 = 101 ⋅884287.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (78921397) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 19730348 + ... + 19730351.

It is an arithmetic number, because the mean of its divisors is an integer number (29595525).

Almost surely, 2^78921398 is an apocalyptic number.

78921398 is a deficient number, since it is larger than the sum of its proper divisors (39460702).

78921398 is a wasteful number, since it uses less digits than its factorization.

78921398 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 39460701.

The product of its digits is 217728, while the sum is 47.

The square root of 78921398 is about 8883.7716089508. The cubic root of 78921398 is about 428.9416880370.

The spelling of 78921398 in words is "seventy-eight million, nine hundred twenty-one thousand, three hundred ninety-eight".