21998697 has 24 divisors (see below), whose sum is σ = 36131616. Its totient is φ = 11829888.

The previous prime is 21998693. The next prime is 21998701. The reversal of 21998697 is 79689912.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (21998693) and next prime (21998701).

It is not a de Polignac number, because 21998697 - 2² = 21998693 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (51).

It is not an unprimeable number, because it can be changed into a prime (21998693) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 1903 + ... + 6900.

It is an arithmetic number, because the mean of its divisors is an integer number (1505484).

Almost surely, 2^21998697 is an apocalyptic number.

It is an amenable number.

21998697 is a deficient number, since it is larger than the sum of its proper divisors (14132919).

21998697 is a wasteful number, since it uses less digits than its factorization.

21998697 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8837 (or 8830 counting only the distinct ones).

The product of its digits is 489888, while the sum is 51.

The square root of 21998697 is about 4690.2768575000. The cubic root of 21998697 is about 280.1984010514.

The spelling of 21998697 in words is "twenty-one million, nine hundred ninety-eight thousand, six hundred ninety-seven".