1264349781 has 18 divisors (see below), whose sum is σ = 1840435350. Its totient is φ = 836380560.

The previous prime is 1264349747. The next prime is 1264349797. The reversal of 1264349781 is 1879434621.

1264349781 is a `hidden beast` number, since 126 + 434 + 97 + 8 + 1 = 666.

It can be written as a sum of positive squares in only one way, i.e., 848556900 + 415792881 = 29130^2 + 20391^2 .

It is not a de Polignac number, because 1264349781 - 2³⁰ = 190607957 is a prime.

It is a super-2 number, since 2×1264349781² = 3197160737429495922, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1264349711) by changing a digit.

It is a polite number, since it can be written in 17 ways as a sum of consecutive naturals, for example, 1301626 + ... + 1302596.

Almost surely, 2^1264349781 is an apocalyptic number.

It is an amenable number.

1264349781 is a deficient number, since it is larger than the sum of its proper divisors (576085569).

1264349781 is an frugal number, since it uses more digits than its factorization.

1264349781 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2097 (or 1123 counting only the distinct ones).

The product of its digits is 290304, while the sum is 45.

The square root of 1264349781 is about 35557.6965086323. The cubic root of 1264349781 is about 1081.3237600299.

The spelling of 1264349781 in words is "one billion, two hundred sixty-four million, three hundred forty-nine thousand, seven hundred eighty-one".