20797021 has 6 divisors (see below), whose sum is σ = 24192510. Its totient is φ = 17825976.

The previous prime is 20797013. The next prime is 20797033. The reversal of 20797021 is 12079702.

It is a happy number.

It can be written as a sum of positive squares in only one way, i.e., 16088121 + 4708900 = 4011^2 + 2170^2 .

It is not a de Polignac number, because 20797021 - 2³ = 20797013 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20797121) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 212166 + ... + 212263.

It is an arithmetic number, because the mean of its divisors is an integer number (4032085).

Almost surely, 2^20797021 is an apocalyptic number.

It is an amenable number.

20797021 is a deficient number, since it is larger than the sum of its proper divisors (3395489).

20797021 is an equidigital number, since it uses as much as digits as its factorization.

20797021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 424443 (or 424436 counting only the distinct ones).

The product of its (nonzero) digits is 1764, while the sum is 28.

The square root of 20797021 is about 4560.3750942220. The cubic root of 20797021 is about 275.0006435247. Note that the first 3 decimals are identical.

The spelling of 20797021 in words is "twenty million, seven hundred ninety-seven thousand, twenty-one".