2778909021 has 72 divisors (see below), whose sum is σ = 4865702400. Its totient is φ = 1521979200.

The previous prime is 2778909017. The next prime is 2778909053. The reversal of 2778909021 is 1209098772.

2778909021 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is not a de Polignac number, because 2778909021 - 2² = 2778909017 is a prime.

It is a hoax number, since the sum of its digits (45) coincides with the sum of the digits of its distinct prime factors.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (2778909061) by changing a digit.

It is a polite number, since it can be written in 71 ways as a sum of consecutive naturals, for example, 1930420 + ... + 1931858.

It is an arithmetic number, because the mean of its divisors is an integer number (67579200).

Almost surely, 2^2778909021 is an apocalyptic number.

2778909021 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

It is an amenable number.

2778909021 is a deficient number, since it is larger than the sum of its proper divisors (2086793379).

2778909021 is a wasteful number, since it uses less digits than its factorization.

2778909021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1639 (or 1629 counting only the distinct ones).

The product of its (nonzero) digits is 127008, while the sum is 45.

The square root of 2778909021 is about 52715.3584925684. The cubic root of 2778909021 is about 1405.9119084349.

The spelling of 2778909021 in words is "two billion, seven hundred seventy-eight million, nine hundred nine thousand, twenty-one".