21116206403231 has 4 divisors (see below), whose sum is σ = 21607280970792. Its totient is φ = 20625131835672.

The previous prime is 21116206403203. The next prime is 21116206403251. The reversal of 21116206403231 is 13230460261112.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21116206403231 is a prime.

It is a super-2 number, since 2×21116206403231² (a number of 27 digits) 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 (21116206403251) 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, 245537283716 + ... + 245537283801.

It is an arithmetic number, because the mean of its divisors is an integer number (5401820242698).

Almost surely, 2^{21116206403231} is an apocalyptic number.

21116206403231 is a deficient number, since it is larger than the sum of its proper divisors (491074567561).

21116206403231 is an equidigital number, since it uses as much as digits as its factorization.

21116206403231 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 491074567560.

The product of its (nonzero) digits is 10368, while the sum is 32.

Adding to 21116206403231 its reverse (13230460261112), we get a palindrome (34346666664343).

The spelling of 21116206403231 in words is "twenty-one trillion, one hundred sixteen billion, two hundred six million, four hundred three thousand, two hundred thirty-one".