1623661 has 4 divisors (see below), whose sum is σ = 1748572. Its totient is φ = 1498752.

The previous prime is 1623647. The next prime is 1623667. The reversal of 1623661 is 1663261.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 1663261 = 37 ⋅44953.

It can be written as a sum of positive squares in 2 ways, for example, as 756900 + 866761 = 870^2 + 931^2 .

It is a cyclic number.

It is not a de Polignac number, because 1623661 - 2⁷ = 1623533 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1623667) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 62436 + ... + 62461.

It is an arithmetic number, because the mean of its divisors is an integer number (437143).

2^1623661 is an apocalyptic number.

It is an amenable number.

1623661 is a deficient number, since it is larger than the sum of its proper divisors (124911).

1623661 is a wasteful number, since it uses less digits than its factorization.

1623661 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 124910.

The product of its digits is 1296, while the sum is 25.

The square root of 1623661 is about 1274.2295711527. The cubic root of 1623661 is about 117.5344338495.

The spelling of 1623661 in words is "one million, six hundred twenty-three thousand, six hundred sixty-one".