21345352531021 has 16 divisors (see below), whose sum is σ = 22985992641600. Its totient is φ = 19747551852288.

The previous prime is 21345352531007. The next prime is 21345352531073. The reversal of 21345352531021 is 12013525354312.

It is a happy number.

It is a cyclic number.

It is not a de Polignac number, because 21345352531021 - 2²³ = 21345344142413 is a prime.

It is a super-2 number, since 2×21345352531021² (a number of 27 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 (21345352531001) 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, 10910971 + ... + 12717703.

It is an arithmetic number, because the mean of its divisors is an integer number (1436624540100).

Almost surely, 2^{21345352531021} is an apocalyptic number.

It is an amenable number.

21345352531021 is a deficient number, since it is larger than the sum of its proper divisors (1640640110579).

21345352531021 is a wasteful number, since it uses less digits than its factorization.

21345352531021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1818588.

The product of its (nonzero) digits is 108000, while the sum is 37.

Adding to 21345352531021 its reverse (12013525354312), we get a palindrome (33358877885333).

The spelling of 21345352531021 in words is "twenty-one trillion, three hundred forty-five billion, three hundred fifty-two million, five hundred thirty-one thousand, twenty-one".