21253444031631 has 16 divisors (see below), whose sum is σ = 32386268217344. Its totient is φ = 12144799740384.

The previous prime is 21253444031507. The next prime is 21253444031663. The reversal of 21253444031631 is 13613044435212.

It is not a de Polignac number, because 21253444031631 - 2¹¹ = 21253444029583 is a prime.

It is a super-2 number, since 2×21253444031631² (a number of 27 digits) contains 22 as substring.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21253444031631.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21253444032631) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 14588661 + ... + 15979233.

It is an arithmetic number, because the mean of its divisors is an integer number (2024141763584).

Almost surely, 2^{21253444031631} is an apocalyptic number.

21253444031631 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

21253444031631 is a deficient number, since it is larger than the sum of its proper divisors (11132824185713).

21253444031631 is a wasteful number, since it uses less digits than its factorization.

21253444031631 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2118390.

The product of its (nonzero) digits is 207360, while the sum is 39.

Adding to 21253444031631 its reverse (13613044435212), we get a palindrome (34866488466843).

The spelling of 21253444031631 in words is "twenty-one trillion, two hundred fifty-three billion, four hundred forty-four million, thirty-one thousand, six hundred thirty-one".