21998069 has 4 divisors (see below), whose sum is σ = 22509696. Its totient is φ = 21486444.

The previous prime is 21998033. The next prime is 21998107. The reversal of 21998069 is 96089912.

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 a de Polignac number, because none of the positive numbers 2^k-21998069 is a prime.

It is a super-2 number, since 2×21998069² = 967830079457522, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21991069) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 255749 + ... + 255834.

It is an arithmetic number, because the mean of its divisors is an integer number (5627424).

Almost surely, 2^21998069 is an apocalyptic number.

It is an amenable number.

21998069 is a deficient number, since it is larger than the sum of its proper divisors (511627).

21998069 is an equidigital number, since it uses as much as digits as its factorization.

21998069 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 511626.

The product of its (nonzero) digits is 69984, while the sum is 44.

The square root of 21998069 is about 4690.2099100147. The cubic root of 21998069 is about 280.1957347379.

The spelling of 21998069 in words is "twenty-one million, nine hundred ninety-eight thousand, sixty-nine".