1561009690 has 16 divisors (see below), whose sum is σ = 2820267720. Its totient is φ = 622081600.

The previous prime is 1561009673. The next prime is 1561009691. The reversal of 1561009690 is 969001651.

It can be written as a sum of positive squares in 4 ways, for example, as 728514081 + 832495609 = 26991^2 + 28853^2 .

It is a super-2 number, since 2×1561009690² = 4873502504547792200, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (1561009691) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 287461 + ... + 292840.

Almost surely, 2^1561009690 is an apocalyptic number.

1561009690 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

1561009690 is a deficient number, since it is larger than the sum of its proper divisors (1259258030).

1561009690 is a wasteful number, since it uses less digits than its factorization.

1561009690 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 580577.

The product of its (nonzero) digits is 14580, while the sum is 37.

The square root of 1561009690 is about 39509.6151588446. The cubic root of 1561009690 is about 1160.0281627130.

The spelling of 1561009690 in words is "one billion, five hundred sixty-one million, nine thousand, six hundred ninety".