21587735356851 has 16 divisors (see below), whose sum is σ = 30301118080640. Its totient is φ = 13633215209280.

The previous prime is 21587735356793. The next prime is 21587735356861. The reversal of 21587735356851 is 15865353778512.

It is a happy number.

It is not a de Polignac number, because 21587735356851 - 2¹³ = 21587735348659 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21587735356861) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 15202810 + ... + 16562031.

It is an arithmetic number, because the mean of its divisors is an integer number (1893819880040).

Almost surely, 2^{21587735356851} is an apocalyptic number.

21587735356851 is a deficient number, since it is larger than the sum of its proper divisors (8713382723789).

21587735356851 is a wasteful number, since it uses less digits than its factorization.

21587735356851 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 31776786.

The product of its digits is 211680000, while the sum is 66.

The spelling of 21587735356851 in words is "twenty-one trillion, five hundred eighty-seven billion, seven hundred thirty-five million, three hundred fifty-six thousand, eight hundred fifty-one".