1628778261 has 16 divisors (see below), whose sum is σ = 2384828928. Its totient is φ = 980598000.

The previous prime is 1628778227. The next prime is 1628778299.

1628778261 is nontrivially palindromic in base 10.

It is not a de Polignac number, because 1628778261 - 2⁶ = 1628778197 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 1628778261.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1628778461) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 158451 + ... + 168416.

It is an arithmetic number, because the mean of its divisors is an integer number (149051808).

Almost surely, 2^1628778261 is an apocalyptic number.

1628778261 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

It is an amenable number.

1628778261 is a deficient number, since it is larger than the sum of its proper divisors (756050667).

1628778261 is a wasteful number, since it uses less digits than its factorization.

1628778261 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 327032.

The product of its digits is 451584, while the sum is 48.

The square root of 1628778261 is about 40358.1250927245. The cubic root of 1628778261 is about 1176.5778135747.

The spelling of 1628778261 in words is "one billion, six hundred twenty-eight million, seven hundred seventy-eight thousand, two hundred sixty-one".