21270631 has 4 divisors (see below), whose sum is σ = 21285432. Its totient is φ = 21255832.

The previous prime is 21270629. The next prime is 21270643. The reversal of 21270631 is 13607212.

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

It is a cyclic number.

It is not a de Polignac number, because 21270631 - 2¹ = 21270629 is a prime.

It is a super-2 number, since 2×21270631² = 904879486276322, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21276631) 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, 4981 + ... + 8206.

It is an arithmetic number, because the mean of its divisors is an integer number (5321358).

Almost surely, 2^21270631 is an apocalyptic number.

21270631 is a deficient number, since it is larger than the sum of its proper divisors (14801).

21270631 is a wasteful number, since it uses less digits than its factorization.

21270631 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 14800.

The product of its (nonzero) digits is 504, while the sum is 22.

The square root of 21270631 is about 4612.0094319071. The cubic root of 21270631 is about 277.0725220322.

Adding to 21270631 its reverse (13607212), we get a palindrome (34877843).

The spelling of 21270631 in words is "twenty-one million, two hundred seventy thousand, six hundred thirty-one".