1861621823551 has 32 divisors (see below), whose sum is σ = 2198840878080. Its totient is φ = 1543172027904.

The previous prime is 1861621823527. The next prime is 1861621823557. The reversal of 1861621823551 is 1553281261681.

It is a cyclic number.

It is not a de Polignac number, because 1861621823551 - 2¹⁵ = 1861621790783 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 1861621823495 and 1861621823504.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1861621823557) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 13449271 + ... + 13586983.

It is an arithmetic number, because the mean of its divisors is an integer number (68713777440).

Almost surely, 2^{1861621823551} is an apocalyptic number.

1861621823551 is a deficient number, since it is larger than the sum of its proper divisors (337219054529).

1861621823551 is a wasteful number, since it uses less digits than its factorization.

1861621823551 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 138295.

The product of its digits is 691200, while the sum is 49.

The spelling of 1861621823551 in words is "one trillion, eight hundred sixty-one billion, six hundred twenty-one million, eight hundred twenty-three thousand, five hundred fifty-one".