78821990 has 16 divisors (see below), whose sum is σ = 152793648. Its totient is φ = 29103456.

The previous prime is 78821983. The next prime is 78822001. The reversal of 78821990 is 9912887.

It is a super-2 number, since 2×78821990² = 12425812215120200, which contains 22 as substring.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 303032 + ... + 303291.

It is an arithmetic number, because the mean of its divisors is an integer number (9549603).

Almost surely, 2^78821990 is an apocalyptic number.

78821990 is a deficient number, since it is larger than the sum of its proper divisors (73971658).

78821990 is a wasteful number, since it uses less digits than its factorization.

78821990 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 606343.

The product of its (nonzero) digits is 72576, while the sum is 44.

The square root of 78821990 is about 8878.1749250620. The cubic root of 78821990 is about 428.7615165756.

The spelling of 78821990 in words is "seventy-eight million, eight hundred twenty-one thousand, nine hundred ninety".