21121443542 has 16 divisors (see below), whose sum is σ = 32241316272. Its totient is φ = 10375184160.

The previous prime is 21121443527. The next prime is 21121443557. The reversal of 21121443542 is 24534412112.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (21121443527) and next prime (21121443557).

It is a super-2 number, since 2×21121443542² (a number of 21 digits) contains 22 as substring.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 161309 + ... + 261272.

It is an arithmetic number, because the mean of its divisors is an integer number (2015082267).

Almost surely, 2^21121443542 is an apocalyptic number.

21121443542 is a deficient number, since it is larger than the sum of its proper divisors (11119872730).

21121443542 is a wasteful number, since it uses less digits than its factorization.

21121443542 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 423023.

The product of its digits is 7680, while the sum is 29.

Adding to 21121443542 its reverse (24534412112), we get a palindrome (45655855654).

The spelling of 21121443542 in words is "twenty-one billion, one hundred twenty-one million, four hundred forty-three thousand, five hundred forty-two".