1649721 has 8 divisors (see below), whose sum is σ = 2295360. Its totient is φ = 1051952.

The previous prime is 1649707. The next prime is 1649737. The reversal of 1649721 is 1279461.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 1649721 - 2⁵ = 1649689 is a prime.

It is not an unprimeable number, because it can be changed into a prime (1649771) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 11886 + ... + 12023.

It is an arithmetic number, because the mean of its divisors is an integer number (286920).

2^1649721 is an apocalyptic number.

It is an amenable number.

1649721 is a deficient number, since it is larger than the sum of its proper divisors (645639).

1649721 is a wasteful number, since it uses less digits than its factorization.

1649721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 23935.

The product of its digits is 3024, while the sum is 30.

The square root of 1649721 is about 1284.4146526726. The cubic root of 1649721 is about 118.1599143734.

The spelling of 1649721 in words is "one million, six hundred forty-nine thousand, seven hundred twenty-one".