21355506031 has 2 divisors, whose sum is σ = 21355506032. Its totient is φ = 21355506030.

The previous prime is 21355505987. The next prime is 21355506061. The reversal of 21355506031 is 13060555312.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21355506031 - 2⁷ = 21355505903 is a prime.

It is a super-2 number, since 2×21355506031² (a number of 21 digits) contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 21355505984 and 21355506002.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21355506061) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10677753015 + 10677753016.

It is an arithmetic number, because the mean of its divisors is an integer number (10677753016).

Almost surely, 2^21355506031 is an apocalyptic number.

21355506031 is a deficient number, since it is larger than the sum of its proper divisors (1).

21355506031 is an equidigital number, since it uses as much as digits as its factorization.

21355506031 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 13500, while the sum is 31.

The spelling of 21355506031 in words is "twenty-one billion, three hundred fifty-five million, five hundred six thousand, thirty-one".