1340642731 has 4 divisors (see below), whose sum is σ = 1360652392. Its totient is φ = 1320633072.

The previous prime is 1340642707. The next prime is 1340642741. The reversal of 1340642731 is 1372460431.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 1372460431 = 107 ⋅12826733.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1340642731 is a prime.

It is a super-2 number, since 2×1340642731² = 3594645864366276722, which contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 1340642693 and 1340642702.

It is not an unprimeable number, because it can be changed into a prime (1340642701) 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, 10004730 + ... + 10004863.

It is an arithmetic number, because the mean of its divisors is an integer number (340163098).

Almost surely, 2^1340642731 is an apocalyptic number.

1340642731 is a deficient number, since it is larger than the sum of its proper divisors (20009661).

1340642731 is an equidigital number, since it uses as much as digits as its factorization.

1340642731 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 20009660.

The product of its (nonzero) digits is 12096, while the sum is 31.

The square root of 1340642731 is about 36614.7884194351. The cubic root of 1340642731 is about 1102.6500104565.

The spelling of 1340642731 in words is "one billion, three hundred forty million, six hundred forty-two thousand, seven hundred thirty-one".