21099877 has 4 divisors (see below), whose sum is σ = 21193056. Its totient is φ = 21006700.

The previous prime is 21099863. The next prime is 21099887. The reversal of 21099877 is 77899012.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 21099877 - 2²³ = 12711269 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21099817) 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 3 ways as a sum of consecutive naturals, for example, 46249 + ... + 46702.

It is an arithmetic number, because the mean of its divisors is an integer number (5298264).

Almost surely, 2^21099877 is an apocalyptic number.

It is an amenable number.

21099877 is a deficient number, since it is larger than the sum of its proper divisors (93179).

21099877 is an equidigital number, since it uses as much as digits as its factorization.

21099877 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 93178.

The product of its (nonzero) digits is 63504, while the sum is 43.

The square root of 21099877 is about 4593.4602425622. The cubic root of 21099877 is about 276.3291118806.

The spelling of 21099877 in words is "twenty-one million, ninety-nine thousand, eight hundred seventy-seven".