1951972109 has 4 divisors (see below), whose sum is σ = 1969880220. Its totient is φ = 1934064000.

The previous prime is 1951972097. The next prime is 1951972159. The reversal of 1951972109 is 9012791591.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 9012791591 = 6473 ⋅1392367.

It can be written as a sum of positive squares in 2 ways, for example, as 1265794084 + 686178025 = 35578^2 + 26195^2 .

It is a cyclic number.

It is not a de Polignac number, because 1951972109 - 2¹⁶ = 1951906573 is a prime.

It is a super-2 number, since 2×1951972109² = 7620390228627815762, which contains 22 as substring.

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 1951972109.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1951972159) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 8953892 + ... + 8954109.

It is an arithmetic number, because the mean of its divisors is an integer number (492470055).

Almost surely, 2^1951972109 is an apocalyptic number.

It is an amenable number.

1951972109 is a deficient number, since it is larger than the sum of its proper divisors (17908111).

1951972109 is a wasteful number, since it uses less digits than its factorization.

1951972109 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 17908110.

The product of its (nonzero) digits is 51030, while the sum is 44.

The square root of 1951972109 is about 44181.1284260599. The cubic root of 1951972109 is about 1249.7540015110.

The spelling of 1951972109 in words is "one billion, nine hundred fifty-one million, nine hundred seventy-two thousand, one hundred nine".