21898647 has 16 divisors (see below), whose sum is σ = 32628960. Its totient is φ = 14515200.

The previous prime is 21898619. The next prime is 21898649. The reversal of 21898647 is 74689812.

It is not a de Polignac number, because 21898647 - 2⁷ = 21898519 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21898649) 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, 2647 + ... + 7127.

It is an arithmetic number, because the mean of its divisors is an integer number (2039310).

Almost surely, 2^21898647 is an apocalyptic number.

21898647 is a gapful number since it is divisible by the number (27) formed by its first and last digit.

21898647 is a deficient number, since it is larger than the sum of its proper divisors (10730313).

21898647 is a wasteful number, since it uses less digits than its factorization.

21898647 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4671 (or 4665 counting only the distinct ones).

The product of its digits is 193536, while the sum is 45.

The square root of 21898647 is about 4679.5990212838. The cubic root of 21898647 is about 279.7729749907.

The spelling of 21898647 in words is "twenty-one million, eight hundred ninety-eight thousand, six hundred forty-seven".