31212112021 has 4 divisors (see below), whose sum is σ = 31212942444. Its totient is φ = 31211281600.

The previous prime is 31212111971. The next prime is 31212112033. The reversal of 31212112021 is 12021121213.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 12021121213 = 1423 ⋅8447731.

It can be written as a sum of positive squares in 2 ways, for example, as 11916123921 + 19295988100 = 109161^2 + 138910^2 .

It is a cyclic number.

It is not a de Polignac number, because 31212112021 - 2²⁵ = 31178557589 is a prime.

It is a super-2 number, since 2×31212112021² (a number of 22 digits) contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 31212111986 and 31212112004.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (31212712021) 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, 356020 + ... + 434941.

It is an arithmetic number, because the mean of its divisors is an integer number (7803235611).

Almost surely, 2^31212112021 is an apocalyptic number.

It is an amenable number.

31212112021 is a deficient number, since it is larger than the sum of its proper divisors (830423).

31212112021 is an equidigital number, since it uses as much as digits as its factorization.

31212112021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 830422.

The product of its (nonzero) digits is 48, while the sum is 16.

Adding to 31212112021 its reverse (12021121213), we get a palindrome (43233233234).

The spelling of 31212112021 in words is "thirty-one billion, two hundred twelve million, one hundred twelve thousand, twenty-one".