1661390 has 16 divisors (see below), whose sum is σ = 3021408. Its totient is φ = 657696.

The previous prime is 1661353. The next prime is 1661431. The reversal of 1661390 is 931661.

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, 224 + ... + 1836.

It is an arithmetic number, because the mean of its divisors is an integer number (188838).

2^1661390 is an apocalyptic number.

1661390 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

1661390 is a deficient number, since it is larger than the sum of its proper divisors (1360018).

1661390 is a wasteful number, since it uses less digits than its factorization.

1661390 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1723.

The product of its (nonzero) digits is 972, while the sum is 26.

The square root of 1661390 is about 1288.9491844134. The cubic root of 1661390 is about 118.4378542676.

The spelling of 1661390 in words is "one million, six hundred sixty-one thousand, three hundred ninety".