21531849786077 has 4 divisors (see below), whose sum is σ = 22798429185276. Its totient is φ = 20265270386880.

The previous prime is 21531849786067. The next prime is 21531849786127. The reversal of 21531849786077 is 77068794813512.

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

It can be written as a sum of positive squares in 2 ways, for example, as 18130385164441 + 3401464621636 = 4257979^2 + 1844306^2 .

It is not a de Polignac number, because 21531849786077 - 2²⁶ = 21531782677213 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21531849785998 and 21531849786016.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21531849786067) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 633289699574 + ... + 633289699607.

It is an arithmetic number, because the mean of its divisors is an integer number (5699607296319).

It is a 1-persistent number, because it is pandigital, but 2⋅21531849786077 = 43063699572154 is not.

Almost surely, 2^{21531849786077} is an apocalyptic number.

It is an amenable number.

21531849786077 is a deficient number, since it is larger than the sum of its proper divisors (1266579399199).

21531849786077 is a wasteful number, since it uses less digits than its factorization.

21531849786077 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1266579399198.

The product of its (nonzero) digits is 142248960, while the sum is 68.

The spelling of 21531849786077 in words is "twenty-one trillion, five hundred thirty-one billion, eight hundred forty-nine million, seven hundred eighty-six thousand, seventy-seven".