21632387 has 8 divisors (see below), whose sum is σ = 24754176. Its totient is φ = 18518472.

The previous prime is 21632339. The next prime is 21632399. The reversal of 21632387 is 78323612.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 21632387 - 2⁶ = 21632323 is a prime.

It is an alternating number because its digits alternate between even and odd.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21632287) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 6188 + ... + 9030.

It is an arithmetic number, because the mean of its divisors is an integer number (3094272).

Almost surely, 2^21632387 is an apocalyptic number.

21632387 is a deficient number, since it is larger than the sum of its proper divisors (3121789).

21632387 is a wasteful number, since it uses less digits than its factorization.

21632387 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3937.

The product of its digits is 12096, while the sum is 32.

The square root of 21632387 is about 4651.0629967783. The cubic root of 21632387 is about 278.6344523007.

Adding to 21632387 its reverse (78323612), we get a palindrome (99955999).

The spelling of 21632387 in words is "twenty-one million, six hundred thirty-two thousand, three hundred eighty-seven".