1491721 has 8 divisors (see below), whose sum is σ = 1859904. Its totient is φ = 1162320.

The previous prime is 1491719. The next prime is 1491727. The reversal of 1491721 is 1271941.

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 1491721 - 2¹ = 1491719 is a prime.

It is an Ulam number.

It is a Duffinian number.

1491721 is a lucky number.

It is not an unprimeable number, because it can be changed into a prime (1491727) 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, 9610 + ... + 9763.

It is an arithmetic number, because the mean of its divisors is an integer number (232488).

2^1491721 is an apocalyptic number.

1491721 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

It is an amenable number.

1491721 is a deficient number, since it is larger than the sum of its proper divisors (368183).

1491721 is a wasteful number, since it uses less digits than its factorization.

1491721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 19391.

The product of its digits is 504, while the sum is 25.

The square root of 1491721 is about 1221.3603071985. The cubic root of 1491721 is about 114.2604336195.

The spelling of 1491721 in words is "one million, four hundred ninety-one thousand, seven hundred twenty-one".