20797977 has 4 divisors (see below), whose sum is σ = 27730640. Its totient is φ = 13865316.

The previous prime is 20797961. The next prime is 20797981. The reversal of 20797977 is 77979702.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is not a de Polignac number, because 20797977 - 2⁴ = 20797961 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20797927) 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, 3466327 + ... + 3466332.

It is an arithmetic number, because the mean of its divisors is an integer number (6932660).

Almost surely, 2^20797977 is an apocalyptic number.

It is an amenable number.

20797977 is a deficient number, since it is larger than the sum of its proper divisors (6932663).

20797977 is an equidigital number, since it uses as much as digits as its factorization.

20797977 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6932662.

The product of its (nonzero) digits is 388962, while the sum is 48.

The square root of 20797977 is about 4560.4799089570. The cubic root of 20797977 is about 275.0048572145.

Adding to 20797977 its sum of digits (48), we get a triangular number (20798025 = T₆₄₄₉).

The spelling of 20797977 in words is "twenty million, seven hundred ninety-seven thousand, nine hundred seventy-seven".