1690726649 has 4 divisors (see below), whose sum is σ = 1695073380. Its totient is φ = 1686379920.

The previous prime is 1690726643. The next prime is 1690726657. The reversal of 1690726649 is 9466270961.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 9466270961 = 7 ⋅1352324423.

It can be written as a sum of positive squares in 2 ways, for example, as 603046249 + 1087680400 = 24557^2 + 32980^2 .

It is a cyclic number.

It is not a de Polignac number, because 1690726649 - 2²⁰ = 1689678073 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 1690726597 and 1690726606.

It is not an unprimeable number, because it can be changed into a prime (1690726643) 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, 2172782 + ... + 2173559.

It is an arithmetic number, because the mean of its divisors is an integer number (423768345).

Almost surely, 2^1690726649 is an apocalyptic number.

It is an amenable number.

1690726649 is a deficient number, since it is larger than the sum of its proper divisors (4346731).

1690726649 is an equidigital number, since it uses as much as digits as its factorization.

1690726649 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4346730.

The product of its (nonzero) digits is 979776, while the sum is 50.

The square root of 1690726649 is about 41118.4465781479. The cubic root of 1690726649 is about 1191.3091185935.

The spelling of 1690726649 in words is "one billion, six hundred ninety million, seven hundred twenty-six thousand, six hundred forty-nine".