1561262666 has 8 divisors (see below), whose sum is σ = 2342338020. Its totient is φ = 780483328.

The previous prime is 1561262663. The next prime is 1561262669. The reversal of 1561262666 is 6662621651.

It is an interprime number because it is at equal distance from previous prime (1561262663) and next prime (1561262669).

It can be written as a sum of positive squares in 2 ways, for example, as 884170225 + 677092441 = 29735^2 + 26021^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a super-2 number, since 2×1561262666² = 4875082224490855112, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (1561262663) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 60311 + ... + 82218.

Almost surely, 2^1561262666 is an apocalyptic number.

1561262666 is a deficient number, since it is larger than the sum of its proper divisors (781075354).

1561262666 is a wasteful number, since it uses less digits than its factorization.

1561262666 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 148008.

The product of its digits is 155520, while the sum is 41.

The square root of 1561262666 is about 39512.8164776949. The cubic root of 1561262666 is about 1160.0908237448.

The spelling of 1561262666 in words is "one billion, five hundred sixty-one million, two hundred sixty-two thousand, six hundred sixty-six".