6661990 has 16 divisors (see below), whose sum is σ = 12271248. Its totient is φ = 2602656.

The previous prime is 6661987. The next prime is 6661997. The reversal of 6661990 is 991666.

It is a super-2 number, since 2×6661990² = 88764221520200, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (6661997) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 7317 + ... + 8176.

It is an arithmetic number, because the mean of its divisors is an integer number (766953).

Almost surely, 2^6661990 is an apocalyptic number.

6661990 is a deficient number, since it is larger than the sum of its proper divisors (5609258).

6661990 is a wasteful number, since it uses less digits than its factorization.

6661990 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 15543.

The product of its (nonzero) digits is 17496, while the sum is 37.

The square root of 6661990 is about 2581.0831059848. The cubic root of 6661990 is about 188.1631863631.

The spelling of 6661990 in words is "six million, six hundred sixty-one thousand, nine hundred ninety".