1071067721 has 4 divisors (see below), whose sum is σ = 1071133200. Its totient is φ = 1071002244.

The previous prime is 1071067687. The next prime is 1071067727. The reversal of 1071067721 is 1277601701.

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, and also a brilliant number, because the two primes have the same length, and also an emirpimes, since its reverse is a distinct semiprime: 1277601701 = 827 ⋅1544863.

It is a cyclic number.

It is not a de Polignac number, because 1071067721 - 2¹⁸ = 1070805577 is a prime.

It is a super-2 number, since 2×1071067721² = 2294372125936267682, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1071067727) 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, 15050 + ... + 48668.

It is an arithmetic number, because the mean of its divisors is an integer number (267783300).

Almost surely, 2^1071067721 is an apocalyptic number.

It is an amenable number.

1071067721 is a deficient number, since it is larger than the sum of its proper divisors (65479).

1071067721 is an equidigital number, since it uses as much as digits as its factorization.

1071067721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 65478.

The product of its (nonzero) digits is 4116, while the sum is 32.

The square root of 1071067721 is about 32727.1709898671. The cubic root of 1071067721 is about 1023.1492188818.

The spelling of 1071067721 in words is "one billion, seventy-one million, sixty-seven thousand, seven hundred twenty-one".