1999951 has 4 divisors (see below), whose sum is σ = 2019472. Its totient is φ = 1980432.

The previous prime is 1999891. The next prime is 1999957. The reversal of 1999951 is 1599991.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 1999951 - 2¹¹ = 1997903 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 1999898 and 1999907.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1999957) 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 3 ways as a sum of consecutive naturals, for example, 9606 + ... + 9811.

It is an arithmetic number, because the mean of its divisors is an integer number (504868).

2^1999951 is an apocalyptic number.

1999951 is a deficient number, since it is larger than the sum of its proper divisors (19521).

1999951 is a wasteful number, since it uses less digits than its factorization.

1999951 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 19520.

The product of its digits is 32805, while the sum is 43.

The square root of 1999951 is about 1414.1962381508. The cubic root of 1999951 is about 125.9910760456.

The spelling of 1999951 in words is "one million, nine hundred ninety-nine thousand, nine hundred fifty-one".