21263131 has 4 divisors (see below), whose sum is σ = 21298432. Its totient is φ = 21227832.

The previous prime is 21263093. The next prime is 21263149. The reversal of 21263131 is 13136212.

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 21263131 - 2²³ = 12874523 is a prime.

It is a super-2 number, since 2×21263131² = 904241479846322, which contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21263099 and 21263108.

It is not an unprimeable number, because it can be changed into a prime (21263161) 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, 16731 + ... + 17956.

It is an arithmetic number, because the mean of its divisors is an integer number (5324608).

Almost surely, 2^21263131 is an apocalyptic number.

21263131 is a deficient number, since it is larger than the sum of its proper divisors (35301).

21263131 is an equidigital number, since it uses as much as digits as its factorization.

21263131 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 35300.

The product of its digits is 216, while the sum is 19.

The square root of 21263131 is about 4611.1962656126. The cubic root of 21263131 is about 277.0399530532.

Adding to 21263131 its reverse (13136212), we get a palindrome (34399343).

The spelling of 21263131 in words is "twenty-one million, two hundred sixty-three thousand, one hundred thirty-one".