21631487 has 8 divisors (see below), whose sum is σ = 21868704. Its totient is φ = 21395968.

The previous prime is 21631483. The next prime is 21631501. The reversal of 21631487 is 78413612.

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

It is a cyclic number.

It is not a de Polignac number, because 21631487 - 2² = 21631483 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21631483) 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, 61103 + ... + 61455.

It is an arithmetic number, because the mean of its divisors is an integer number (2733588).

Almost surely, 2^21631487 is an apocalyptic number.

21631487 is a deficient number, since it is larger than the sum of its proper divisors (237217).

21631487 is a wasteful number, since it uses less digits than its factorization.

21631487 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 849.

The product of its digits is 8064, while the sum is 32.

The square root of 21631487 is about 4650.9662436960. The cubic root of 21631487 is about 278.6305881180.

The spelling of 21631487 in words is "twenty-one million, six hundred thirty-one thousand, four hundred eighty-seven".