20821924 has 6 divisors (see below), whose sum is σ = 36438374. Its totient is φ = 10410960.

The previous prime is 20821909. The next prime is 20821949. The reversal of 20821924 is 42912802.

It can be written as a sum of positive squares in only one way, i.e., 20412324 + 409600 = 4518^2 + 640^2 .

It is a junction number, because it is equal to n+sod(n) for n = 20821892 and 20821901.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 2602737 + ... + 2602744.

Almost surely, 2^20821924 is an apocalyptic number.

It is an amenable number.

20821924 is a deficient number, since it is larger than the sum of its proper divisors (15616450).

20821924 is a wasteful number, since it uses less digits than its factorization.

20821924 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5205485 (or 5205483 counting only the distinct ones).

The product of its (nonzero) digits is 2304, while the sum is 28.

The square root of 20821924 is about 4563.1046448663. The cubic root of 20821924 is about 275.1103645174.

The spelling of 20821924 in words is "twenty million, eight hundred twenty-one thousand, nine hundred twenty-four".