21121031131 has 4 divisors (see below), whose sum is σ = 21122255752. Its totient is φ = 21119806512.

The previous prime is 21121031119. The next prime is 21121031189. The reversal of 21121031131 is 13113012112.

It is a happy number.

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 21121031131 - 2¹⁵ = 21120998363 is a prime.

It is a super-2 number, since 2×21121031131² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21121031231) 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, 586065 + ... + 621058.

It is an arithmetic number, because the mean of its divisors is an integer number (5280563938).

Almost surely, 2^21121031131 is an apocalyptic number.

21121031131 is a deficient number, since it is larger than the sum of its proper divisors (1224621).

21121031131 is a wasteful number, since it uses less digits than its factorization.

21121031131 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1224620.

The product of its (nonzero) digits is 36, while the sum is 16.

Adding to 21121031131 its reverse (13113012112), we get a palindrome (34234043243).

The spelling of 21121031131 in words is "twenty-one billion, one hundred twenty-one million, thirty-one thousand, one hundred thirty-one".