1621649 has 4 divisors (see below), whose sum is σ = 1634160. Its totient is φ = 1609140.

The previous prime is 1621643. The next prime is 1621657. The reversal of 1621649 is 9461261.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 9461261 = 107 ⋅88423.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1621649 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1621643) 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, 6059 + ... + 6320.

It is an arithmetic number, because the mean of its divisors is an integer number (408540).

2^1621649 is an apocalyptic number.

It is an amenable number.

1621649 is a deficient number, since it is larger than the sum of its proper divisors (12511).

1621649 is a wasteful number, since it uses less digits than its factorization.

1621649 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 12510.

The product of its digits is 2592, while the sum is 29.

The square root of 1621649 is about 1273.4398297525. The cubic root of 1621649 is about 117.4858652078.

The spelling of 1621649 in words is "one million, six hundred twenty-one thousand, six hundred forty-nine".