1949551891 has 16 divisors (see below), whose sum is σ = 2387556864. Its totient is φ = 1553791104.

The previous prime is 1949551871. The next prime is 1949551913. The reversal of 1949551891 is 1981559491.

It is a happy number.

It is a cyclic number.

It is not a de Polignac number, because 1949551891 - 2²¹ = 1947454739 is a prime.

It is not an unprimeable number, because it can be changed into a prime (1949551831) 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, 88815 + ... + 108568.

It is an arithmetic number, because the mean of its divisors is an integer number (149222304).

Almost surely, 2^1949551891 is an apocalyptic number.

1949551891 is a deficient number, since it is larger than the sum of its proper divisors (438004973).

1949551891 is a wasteful number, since it uses less digits than its factorization.

1949551891 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 197490.

The product of its digits is 583200, while the sum is 52.

The square root of 1949551891 is about 44153.7302048196. The cubic root of 1949551891 is about 1249.2372714374.

The spelling of 1949551891 in words is "one billion, nine hundred forty-nine million, five hundred fifty-one thousand, eight hundred ninety-one".