1861972849 has 16 divisors (see below), whose sum is σ = 2139986880. Its totient is φ = 1602236160.

The previous prime is 1861972841. The next prime is 1861972897. The reversal of 1861972849 is 9482791681.

It is a happy number.

It is a cyclic number.

It is not a de Polignac number, because 1861972849 - 2³ = 1861972841 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 1861972849.

It is not an unprimeable number, because it can be changed into a prime (1861972841) 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, 296389 + ... + 302605.

It is an arithmetic number, because the mean of its divisors is an integer number (133749180).

Almost surely, 2^1861972849 is an apocalyptic number.

1861972849 is a gapful number since it is divisible by the number (19) formed by its first and last digit.

It is an amenable number.

1861972849 is a deficient number, since it is larger than the sum of its proper divisors (278014031).

1861972849 is a wasteful number, since it uses less digits than its factorization.

1861972849 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7680.

The product of its digits is 1741824, while the sum is 55.

The square root of 1861972849 is about 43150.5834143642. The cubic root of 1861972849 is about 1230.2436005941.

The spelling of 1861972849 in words is "one billion, eight hundred sixty-one million, nine hundred seventy-two thousand, eight hundred forty-nine".