21677661 has 12 divisors (see below), whose sum is σ = 32673888. Its totient is φ = 13823304.

The previous prime is 21677653. The next prime is 21677681. The reversal of 21677661 is 16677612.

It is not a de Polignac number, because 21677661 - 2³ = 21677653 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21677611) 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 11 ways as a sum of consecutive naturals, for example, 52155 + ... + 52568.

It is an arithmetic number, because the mean of its divisors is an integer number (2722824).

Almost surely, 2^21677661 is an apocalyptic number.

It is an amenable number.

21677661 is a deficient number, since it is larger than the sum of its proper divisors (10996227).

21677661 is a wasteful number, since it uses less digits than its factorization.

21677661 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 104752 (or 104749 counting only the distinct ones).

The product of its digits is 21168, while the sum is 36.

The square root of 21677661 is about 4655.9275123223. The cubic root of 21677661 is about 278.8286997181.

It can be divided in two parts, 216 and 77661, that added together give a palindrome (77877).

The spelling of 21677661 in words is "twenty-one million, six hundred seventy-seven thousand, six hundred sixty-one".