821861240651 has 4 divisors (see below), whose sum is σ = 896575898904. Its totient is φ = 747146582400.

The previous prime is 821861240639. The next prime is 821861240677. The reversal of 821861240651 is 156042168128.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 821861240651 - 2¹⁴ = 821861224267 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (821861248651) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 37357329110 + ... + 37357329131.

It is an arithmetic number, because the mean of its divisors is an integer number (224143974726).

Almost surely, 2^821861240651 is an apocalyptic number.

821861240651 is a deficient number, since it is larger than the sum of its proper divisors (74714658253).

821861240651 is a wasteful number, since it uses less digits than its factorization.

821861240651 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 74714658252.

The product of its (nonzero) digits is 184320, while the sum is 44.

The spelling of 821861240651 in words is "eight hundred twenty-one billion, eight hundred sixty-one million, two hundred forty thousand, six hundred fifty-one".