391720050 has 90 divisors (see below), whose sum is σ = 1091912349. Its totient is φ = 104122800.

The previous prime is 391720033. The next prime is 391720079. The reversal of 391720050 is 50027193.

It can be written as a sum of positive squares in 2 ways, for example, as 383885649 + 7834401 = 19593^2 + 2799^2 .

It is a tau number, because it is divible by the number of its divisors (90).

It is an ABA number since it can be written as A⋅B^A, here for A=2, B=13995.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a junction number, because it is equal to n+sod(n) for n = 391719996 and 391720023.

It is an unprimeable number.

It is a polite number, since it can be written in 44 ways as a sum of consecutive naturals, for example, 1259395 + ... + 1259705.

Almost surely, 2^391720050 is an apocalyptic number.

391720050 is a gapful number since it is divisible by the number (30) formed by its first and last digit.

It is a practical number, because each smaller number is the sum of distinct divisors of 391720050

391720050 is an abundant number, since it is smaller than the sum of its proper divisors (700192299).

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

391720050 is an equidigital number, since it uses as much as digits as its factorization.

391720050 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 646 (or 321 counting only the distinct ones).

The product of its (nonzero) digits is 1890, while the sum is 27.

The square root of 391720050 is about 19791.9188054115. The cubic root of 391720050 is about 731.6868789779.

The spelling of 391720050 in words is "three hundred ninety-one million, seven hundred twenty thousand, fifty".