21020010031 has 4 divisors (see below), whose sum is σ = 21333741592. Its totient is φ = 20706278472.

The previous prime is 21020010013. The next prime is 21020010041. The reversal of 21020010031 is 13001002012.

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 21020010031 - 2¹⁹ = 21019485743 is a prime.

It is a super-2 number, since 2×21020010031² (a number of 21 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 (21020010041) 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, 156865680 + ... + 156865813.

It is an arithmetic number, because the mean of its divisors is an integer number (5333435398).

Almost surely, 2^21020010031 is an apocalyptic number.

21020010031 is a deficient number, since it is larger than the sum of its proper divisors (313731561).

21020010031 is an equidigital number, since it uses as much as digits as its factorization.

21020010031 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 313731560.

The product of its (nonzero) digits is 12, while the sum is 10.

Adding to 21020010031 its reverse (13001002012), we get a palindrome (34021012043).

The spelling of 21020010031 in words is "twenty-one billion, twenty million, ten thousand, thirty-one".