21521020677 has 16 divisors (see below), whose sum is σ = 30917322240. Its totient is φ = 13237129152.

The previous prime is 21521020667. The next prime is 21521020687. The reversal of 21521020677 is 77602012512.

It is an interprime number because it is at equal distance from previous prime (21521020667) and next prime (21521020687).

It is not a de Polignac number, because 21521020677 - 2¹⁸ = 21520758533 is a prime.

It is a super-4 number, since 4×21521020677⁴ (a number of 42 digits) contains 4444 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21521020607) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 56853 + ... + 215114.

It is an arithmetic number, because the mean of its divisors is an integer number (1932332640).

Almost surely, 2^21521020677 is an apocalyptic number.

It is an amenable number.

21521020677 is a deficient number, since it is larger than the sum of its proper divisors (9396301563).

21521020677 is a wasteful number, since it uses less digits than its factorization.

21521020677 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 274012.

The product of its (nonzero) digits is 11760, while the sum is 33.

The spelling of 21521020677 in words is "twenty-one billion, five hundred twenty-one million, twenty thousand, six hundred seventy-seven".