21631598 has 4 divisors (see below), whose sum is σ = 32447400. Its totient is φ = 10815798.

The previous prime is 21631591. The next prime is 21631607. The reversal of 21631598 is 89513612.

It is a semiprime because it is the product of two primes.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21631591) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5407898 + ... + 5407901.

It is an arithmetic number, because the mean of its divisors is an integer number (8111850).

Almost surely, 2^21631598 is an apocalyptic number.

21631598 is a deficient number, since it is larger than the sum of its proper divisors (10815802).

21631598 is a wasteful number, since it uses less digits than its factorization.

21631598 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10815801.

The product of its digits is 12960, while the sum is 35.

The square root of 21631598 is about 4650.9781766850. The cubic root of 21631598 is about 278.6310647064.

The spelling of 21631598 in words is "twenty-one million, six hundred thirty-one thousand, five hundred ninety-eight".