21116252621 has 4 divisors (see below), whose sum is σ = 21117356700. Its totient is φ = 21115148544.

The previous prime is 21116252617. The next prime is 21116252657. The reversal of 21116252621 is 12625261112.

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 8664817225 + 12451435396 = 93085^2 + 111586^2 .

It is a cyclic number.

It is not a de Polignac number, because 21116252621 - 2² = 21116252617 is a prime.

It is a super-2 number, since 2×21116252621² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21116252021) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 522836 + ... + 561773.

It is an arithmetic number, because the mean of its divisors is an integer number (5279339175).

Almost surely, 2^21116252621 is an apocalyptic number.

It is an amenable number.

21116252621 is a deficient number, since it is larger than the sum of its proper divisors (1104079).

21116252621 is a wasteful number, since it uses less digits than its factorization.

21116252621 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1104078.

The product of its digits is 2880, while the sum is 29.

The spelling of 21116252621 in words is "twenty-one billion, one hundred sixteen million, two hundred fifty-two thousand, six hundred twenty-one".