1951081561 has 24 divisors (see below), whose sum is σ = 2348801280. Its totient is φ = 1609444320.

The previous prime is 1951081553. The next prime is 1951081577. The reversal of 1951081561 is 1651801591.

It is not a de Polignac number, because 1951081561 - 2³ = 1951081553 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 1951081561.

It is not an unprimeable number, because it can be changed into a prime (1951081501) 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, 82296 + ... + 103318.

It is an arithmetic number, because the mean of its divisors is an integer number (97866720).

Almost surely, 2^1951081561 is an apocalyptic number.

1951081561 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

It is an amenable number.

1951081561 is a deficient number, since it is larger than the sum of its proper divisors (397719719).

1951081561 is a wasteful number, since it uses less digits than its factorization.

1951081561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 21117 (or 21106 counting only the distinct ones).

The product of its (nonzero) digits is 10800, while the sum is 37.

The square root of 1951081561 is about 44171.0489008355. The cubic root of 1951081561 is about 1249.5639142277.

The spelling of 1951081561 in words is "one billion, nine hundred fifty-one million, eighty-one thousand, five hundred sixty-one".