1249999981 has 4 divisors (see below), whose sum is σ = 1279069792. Its totient is φ = 1220930172.

The previous prime is 1249999973. The next prime is 1249999991. The reversal of 1249999981 is 1899999421.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 1899999421 = 13679 ⋅138899.

It is a cyclic number.

It is not a de Polignac number, because 1249999981 - 2³ = 1249999973 is a prime.

It is a super-2 number, since 2×1249999981² = 3124999905000000722, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1249999991) 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, 14534841 + ... + 14534926.

It is an arithmetic number, because the mean of its divisors is an integer number (319767448).

Almost surely, 2^1249999981 is an apocalyptic number.

It is an amenable number.

1249999981 is a deficient number, since it is larger than the sum of its proper divisors (29069811).

1249999981 is an equidigital number, since it uses as much as digits as its factorization.

1249999981 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 29069810.

The product of its digits is 3779136, while the sum is 61.

The square root of 1249999981 is about 35355.3387906268. The cubic root of 1249999981 is about 1077.2173395580.

The spelling of 1249999981 in words is "one billion, two hundred forty-nine million, nine hundred ninety-nine thousand, nine hundred eighty-one".