21420121031 has 4 divisors (see below), whose sum is σ = 21824274312. Its totient is φ = 21015967752.

The previous prime is 21420121003. The next prime is 21420121039. The reversal of 21420121031 is 13012102412.

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 21420121031 - 2²⁶ = 21353012167 is a prime.

It is a super-2 number, since 2×21420121031² (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 (21420121039) 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, 202076561 + ... + 202076666.

It is an arithmetic number, because the mean of its divisors is an integer number (5456068578).

Almost surely, 2^21420121031 is an apocalyptic number.

21420121031 is a deficient number, since it is larger than the sum of its proper divisors (404153281).

21420121031 is an equidigital number, since it uses as much as digits as its factorization.

21420121031 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 404153280.

The product of its (nonzero) digits is 96, while the sum is 17.

Adding to 21420121031 its reverse (13012102412), we get a palindrome (34432223443).

The spelling of 21420121031 in words is "twenty-one billion, four hundred twenty million, one hundred twenty-one thousand, thirty-one".