740821 has 4 divisors (see below), whose sum is σ = 744544. Its totient is φ = 737100.

The previous prime is 740801. The next prime is 740849. The reversal of 740821 is 128047.

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.

It is a cyclic number.

It is not a de Polignac number, because 740821 - 2⁷ = 740693 is a prime.

It is an Ulam number.

It is a Duffinian number.

740821 is a lucky number.

It is a junction number, because it is equal to n+sod(n) for n = 740792 and 740801.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (740801) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1545 + ... + 1966.

It is an arithmetic number, because the mean of its divisors is an integer number (186136).

2⁷⁴⁰⁸²¹ is an apocalyptic number.

It is an amenable number.

740821 is a deficient number, since it is larger than the sum of its proper divisors (3723).

740821 is a wasteful number, since it uses less digits than its factorization.

740821 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3722.

The product of its (nonzero) digits is 448, while the sum is 22.

The square root of 740821 is about 860.7095909771. The cubic root of 740821 is about 90.4838549590.

Adding to 740821 its reverse (128047), we get a palindrome (868868).

The spelling of 740821 in words is "seven hundred forty thousand, eight hundred twenty-one".