21198761 has 4 divisors (see below), whose sum is σ = 21882624. Its totient is φ = 20514900.

The previous prime is 21198757. The next prime is 21198767. The reversal of 21198761 is 16789112.

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 21198761 - 2² = 21198757 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21198767) 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, 341885 + ... + 341946.

It is an arithmetic number, because the mean of its divisors is an integer number (5470656).

Almost surely, 2^21198761 is an apocalyptic number.

It is an amenable number.

21198761 is a deficient number, since it is larger than the sum of its proper divisors (683863).

21198761 is an equidigital number, since it uses as much as digits as its factorization.

21198761 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 683862.

The product of its digits is 6048, while the sum is 35.

The square root of 21198761 is about 4604.2112245204. The cubic root of 21198761 is about 276.7601089186.

The spelling of 21198761 in words is "twenty-one million, one hundred ninety-eight thousand, seven hundred sixty-one".