821689725 has 24 divisors (see below), whose sum is σ = 1361078560. Its totient is φ = 437411520.

The previous prime is 821689723. The next prime is 821689727. The reversal of 821689725 is 527986128.

It is an interprime number because it is at equal distance from previous prime (821689723) and next prime (821689727).

It is not a de Polignac number, because 821689725 - 2¹ = 821689723 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (821689721) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 31011 + ... + 51039.

Almost surely, 2^821689725 is an apocalyptic number.

It is an amenable number.

821689725 is a deficient number, since it is larger than the sum of its proper divisors (539388835).

821689725 is a wasteful number, since it uses less digits than its factorization.

821689725 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 20589 (or 20584 counting only the distinct ones).

The product of its digits is 483840, while the sum is 48.

The square root of 821689725 is about 28665.1308212609. The cubic root of 821689725 is about 936.6326342136.

The spelling of 821689725 in words is "eight hundred twenty-one million, six hundred eighty-nine thousand, seven hundred twenty-five".