2051778821 has 8 divisors (see below), whose sum is σ = 2179954080. Its totient is φ = 1925622288.

The previous prime is 2051778811. The next prime is 2051778851. The reversal of 2051778821 is 1288771502.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 2051778821 - 2¹⁰ = 2051777797 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 (2051778811) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 502586 + ... + 506651.

It is an arithmetic number, because the mean of its divisors is an integer number (272494260).

Almost surely, 2^2051778821 is an apocalyptic number.

It is an amenable number.

2051778821 is a deficient number, since it is larger than the sum of its proper divisors (128175259).

2051778821 is a wasteful number, since it uses less digits than its factorization.

2051778821 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1009363.

The product of its (nonzero) digits is 62720, while the sum is 41.

The square root of 2051778821 is about 45296.5652229835. The cubic root of 2051778821 is about 1270.7014169486.

The spelling of 2051778821 in words is "two billion, fifty-one million, seven hundred seventy-eight thousand, eight hundred twenty-one".