20821634 has 8 divisors (see below), whose sum is σ = 33069708. Its totient is φ = 9798400.

The previous prime is 20821627. The next prime is 20821637. The reversal of 20821634 is 43612802.

It can be written as a sum of positive squares in 2 ways, for example, as 19492225 + 1329409 = 4415^2 + 1153^2 .

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

It is not an unprimeable number, because it can be changed into a prime (20821637) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 306167 + ... + 306234.

Almost surely, 2^20821634 is an apocalyptic number.

20821634 is a deficient number, since it is larger than the sum of its proper divisors (12248074).

20821634 is a wasteful number, since it uses less digits than its factorization.

20821634 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 612420.

The product of its (nonzero) digits is 2304, while the sum is 26.

The square root of 20821634 is about 4563.0728681449. The cubic root of 20821634 is about 275.1090872999.

The spelling of 20821634 in words is "twenty million, eight hundred twenty-one thousand, six hundred thirty-four".