21998055 has 16 divisors (see below), whose sum is σ = 35424864. Its totient is φ = 11656320.

The previous prime is 21998033. The next prime is 21998107. The reversal of 21998055 is 55089912.

It is a de Polignac number, because none of the positive numbers 2^k-21998055 is a prime.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 2316 + ... + 7025.

It is an arithmetic number, because the mean of its divisors is an integer number (2214054).

Almost surely, 2^21998055 is an apocalyptic number.

21998055 is a deficient number, since it is larger than the sum of its proper divisors (13426809).

21998055 is a wasteful number, since it uses less digits than its factorization.

21998055 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9506.

The product of its (nonzero) digits is 32400, while the sum is 39.

The square root of 21998055 is about 4690.2084175439. The cubic root of 21998055 is about 280.1956752972.

The spelling of 21998055 in words is "twenty-one million, nine hundred ninety-eight thousand, fifty-five".