2151778925 has 6 divisors (see below), whose sum is σ = 2668205898. Its totient is φ = 1721423120.

The previous prime is 2151778921. The next prime is 2151778939. The reversal of 2151778925 is 5298771512.

It can be written as a sum of positive squares in 3 ways, for example, as 698492041 + 1453286884 = 26429^2 + 38122^2 .

It is not a de Polignac number, because 2151778925 - 2² = 2151778921 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 2151778925.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (2151778921) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 43035554 + ... + 43035603.

It is an arithmetic number, because the mean of its divisors is an integer number (444700983).

Almost surely, 2^2151778925 is an apocalyptic number.

2151778925 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

2151778925 is a deficient number, since it is larger than the sum of its proper divisors (516426973).

2151778925 is an equidigital number, since it uses as much as digits as its factorization.

2151778925 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 86071167 (or 86071162 counting only the distinct ones).

The product of its digits is 352800, while the sum is 47.

The square root of 2151778925 is about 46387.2711527634. The cubic root of 2151778925 is about 1291.0187503664.

The spelling of 2151778925 in words is "two billion, one hundred fifty-one million, seven hundred seventy-eight thousand, nine hundred twenty-five".