21198631 has 2 divisors, whose sum is σ = 21198632. Its totient is φ = 21198630.

The previous prime is 21198559. The next prime is 21198673. The reversal of 21198631 is 13689112.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21198631 - 2⁷ = 21198503 is a prime.

It is a super-2 number, since 2×21198631² = 898763912548322, which contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 21198593 and 21198602.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21198731) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10599315 + 10599316.

It is an arithmetic number, because the mean of its divisors is an integer number (10599316).

Almost surely, 2^21198631 is an apocalyptic number.

21198631 is a deficient number, since it is larger than the sum of its proper divisors (1).

21198631 is an equidigital number, since it uses as much as digits as its factorization.

21198631 is an evil number, because the sum of its binary digits is even.

The product of its digits is 2592, while the sum is 31.

The square root of 21198631 is about 4604.1971069884. The cubic root of 21198631 is about 276.7595431797.

The spelling of 21198631 in words is "twenty-one million, one hundred ninety-eight thousand, six hundred thirty-one".