21677891 has 12 divisors (see below), whose sum is σ = 23212728. Its totient is φ = 20231904.

The previous prime is 21677881. The next prime is 21677899. The reversal of 21677891 is 19877612.

It is a de Polignac number, because none of the positive numbers 2^k-21677891 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21677899) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 22271 + ... + 23223.

It is an arithmetic number, because the mean of its divisors is an integer number (1934394).

Almost surely, 2^21677891 is an apocalyptic number.

21677891 is a deficient number, since it is larger than the sum of its proper divisors (1534837).

21677891 is an equidigital number, since it uses as much as digits as its factorization.

21677891 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1042 (or 1019 counting only the distinct ones).

The product of its digits is 42336, while the sum is 41.

The square root of 21677891 is about 4655.9522119541. The cubic root of 21677891 is about 278.8296858389.

The spelling of 21677891 in words is "twenty-one million, six hundred seventy-seven thousand, eight hundred ninety-one".