1517720990 has 8 divisors (see below), whose sum is σ = 2731897800. Its totient is φ = 607088392.

The previous prime is 1517720989. The next prime is 1517720999. The reversal of 1517720990 is 990277151.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1517720999) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 75886040 + ... + 75886059.

It is an arithmetic number, because the mean of its divisors is an integer number (341487225).

Almost surely, 2^1517720990 is an apocalyptic number.

1517720990 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

1517720990 is a deficient number, since it is larger than the sum of its proper divisors (1214176810).

1517720990 is a wasteful number, since it uses less digits than its factorization.

1517720990 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 151772106.

The product of its (nonzero) digits is 39690, while the sum is 41.

The square root of 1517720990 is about 38957.9387288393. The cubic root of 1517720990 is about 1149.2044882695.

The spelling of 1517720990 in words is "one billion, five hundred seventeen million, seven hundred twenty thousand, nine hundred ninety".