1651551561 has 24 divisors (see below), whose sum is σ = 2622956544. Its totient is φ = 993051360.

The previous prime is 1651551533. The next prime is 1651551563.

It is a happy number.

1651551561 is a `hidden beast` number, since 1 + 6 + 51 + 551 + 56 + 1 = 666.

1651551561 is nontrivially palindromic in base 10.

It is not a de Polignac number, because 1651551561 - 2⁵ = 1651551529 is a prime.

It is not an unprimeable number, because it can be changed into a prime (1651551563) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 53106 + ... + 78251.

It is an arithmetic number, because the mean of its divisors is an integer number (109289856).

Almost surely, 2^1651551561 is an apocalyptic number.

1651551561 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

It is an amenable number.

1651551561 is a deficient number, since it is larger than the sum of its proper divisors (971404983).

1651551561 is a wasteful number, since it uses less digits than its factorization.

1651551561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 131501 (or 131498 counting only the distinct ones).

The product of its digits is 22500, while the sum is 36.

The square root of 1651551561 is about 40639.2859312267. The cubic root of 1651551561 is about 1182.0360236215.

The spelling of 1651551561 in words is "one billion, six hundred fifty-one million, five hundred fifty-one thousand, five hundred sixty-one".