1264137981 has 4 divisors (see below), whose sum is σ = 1685517312. Its totient is φ = 842758652.

The previous prime is 1264137961. The next prime is 1264137997. The reversal of 1264137981 is 1897314621.

It is a happy number.

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.

It is a cyclic number.

It is not a de Polignac number, because 1264137981 - 2¹⁹ = 1263613693 is a prime.

It is a super-2 number, since 2×1264137981² = 3196089670013512722, which contains 22 as substring.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1264137961) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 210689661 + ... + 210689666.

It is an arithmetic number, because the mean of its divisors is an integer number (421379328).

Almost surely, 2^1264137981 is an apocalyptic number.

It is an amenable number.

1264137981 is a deficient number, since it is larger than the sum of its proper divisors (421379331).

1264137981 is an equidigital number, since it uses as much as digits as its factorization.

1264137981 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 421379330.

The product of its digits is 72576, while the sum is 42.

The square root of 1264137981 is about 35554.7181257284. The cubic root of 1264137981 is about 1081.2633766441.

The spelling of 1264137981 in words is "one billion, two hundred sixty-four million, one hundred thirty-seven thousand, nine hundred eighty-one".