20777742421 has 4 divisors (see below), whose sum is σ = 20785559200. Its totient is φ = 20769925644.

The previous prime is 20777742413. The next prime is 20777742439. The reversal of 20777742421 is 12424777702.

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, and also an emirpimes, since its reverse is a distinct semiprime: 12424777702 = 2 ⋅6212388851.

It is a cyclic number.

It is not a de Polignac number, because 20777742421 - 2³ = 20777742413 is a prime.

It is a super-2 number, since 2×20777742421² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20777742221) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3904401 + ... + 3909718.

It is an arithmetic number, because the mean of its divisors is an integer number (5196389800).

Almost surely, 2^20777742421 is an apocalyptic number.

It is an amenable number.

20777742421 is a deficient number, since it is larger than the sum of its proper divisors (7816779).

20777742421 is an equidigital number, since it uses as much as digits as its factorization.

20777742421 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7816778.

The product of its (nonzero) digits is 307328, while the sum is 43.

The spelling of 20777742421 in words is "twenty billion, seven hundred seventy-seven million, seven hundred forty-two thousand, four hundred twenty-one".