1628721 has 16 divisors (see below), whose sum is σ = 2433600. Its totient is φ = 1076544.

The previous prime is 1628701. The next prime is 1628729. The reversal of 1628721 is 1278261.

It is not a de Polignac number, because 1628721 - 2⁵ = 1628689 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (27).

1628721 is a lucky number.

It is a plaindrome in base 12.

It is not an unprimeable number, because it can be changed into a prime (1628729) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 4665 + ... + 5001.

It is an arithmetic number, because the mean of its divisors is an integer number (152100).

2^1628721 is an apocalyptic number.

It is an amenable number.

1628721 is a deficient number, since it is larger than the sum of its proper divisors (804879).

1628721 is a wasteful number, since it uses less digits than its factorization.

1628721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 525 (or 519 counting only the distinct ones).

The product of its digits is 1344, while the sum is 27.

The square root of 1628721 is about 1276.2135401256. The cubic root of 1628721 is about 117.6564025569.

The spelling of 1628721 in words is "one million, six hundred twenty-eight thousand, seven hundred twenty-one".