1200001581 has 8 divisors (see below), whose sum is σ = 1777780160. Its totient is φ = 800001036.

The previous prime is 1200001573. The next prime is 1200001589. The reversal of 1200001581 is 1851000021.

It is an interprime number because it is at equal distance from previous prime (1200001573) and next prime (1200001589).

It is not a de Polignac number, because 1200001581 - 2³ = 1200001573 is a prime.

It is a super-2 number, since 2×1200001581² = 2880007588804999122, which contains 22 as substring.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1200001589) 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, 22222225 + ... + 22222278.

It is an arithmetic number, because the mean of its divisors is an integer number (222222520).

Almost surely, 2^1200001581 is an apocalyptic number.

It is an amenable number.

1200001581 is a deficient number, since it is larger than the sum of its proper divisors (577778579).

1200001581 is an equidigital number, since it uses as much as digits as its factorization.

1200001581 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 44444512 (or 44444506 counting only the distinct ones).

The product of its (nonzero) digits is 80, while the sum is 18.

The square root of 1200001581 is about 34641.0389711394. The cubic root of 1200001581 is about 1062.6590358666.

The spelling of 1200001581 in words is "one billion, two hundred million, one thousand, five hundred eighty-one".