20820261 has 32 divisors (see below), whose sum is σ = 34864128. Its totient is φ = 10736640.

The previous prime is 20820259. The next prime is 20820311. The reversal of 20820261 is 16202802.

It is not a de Polignac number, because 20820261 - 2¹ = 20820259 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (21).

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20820211) 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 31 ways as a sum of consecutive naturals, for example, 44350 + ... + 44816.

It is an arithmetic number, because the mean of its divisors is an integer number (1089504).

Almost surely, 2^20820261 is an apocalyptic number.

20820261 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

It is an amenable number.

20820261 is a deficient number, since it is larger than the sum of its proper divisors (14043867).

20820261 is a wasteful number, since it uses less digits than its factorization.

20820261 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 681.

The product of its (nonzero) digits is 384, while the sum is 21.

The square root of 20820261 is about 4562.9224188014. The cubic root of 20820261 is about 275.1030401748.

The spelling of 20820261 in words is "twenty million, eight hundred twenty thousand, two hundred sixty-one".