2171620779 has 12 divisors (see below), whose sum is σ = 2922272808. Its totient is φ = 1434368320.

The previous prime is 2171620757. The next prime is 2171620799. The reversal of 2171620779 is 9770261712.

It is not a de Polignac number, because 2171620779 - 2⁹ = 2171620267 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 2171620779.

It is not an unprimeable number, because it can be changed into a prime (2171620799) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 856744 + ... + 859274.

It is an arithmetic number, because the mean of its divisors is an integer number (243522734).

Almost surely, 2^2171620779 is an apocalyptic number.

2171620779 is a deficient number, since it is larger than the sum of its proper divisors (750652029).

2171620779 is an frugal number, since it uses more digits than its factorization.

2171620779 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5178 (or 2647 counting only the distinct ones).

The product of its (nonzero) digits is 74088, while the sum is 42.

The square root of 2171620779 is about 46600.6521306301. The cubic root of 2171620779 is about 1294.9748366979.

The spelling of 2171620779 in words is "two billion, one hundred seventy-one million, six hundred twenty thousand, seven hundred seventy-nine".