21405210042 has 32 divisors (see below), whose sum is σ = 43320018240. Its totient is φ = 7050243200.

The previous prime is 21405210037. The next prime is 21405210077. The reversal of 21405210042 is 24001250412.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 848917 + ... + 873767.

It is an arithmetic number, because the mean of its divisors is an integer number (1353750570).

Almost surely, 2^21405210042 is an apocalyptic number.

21405210042 is an abundant number, since it is smaller than the sum of its proper divisors (21914808198).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21405210042 is a wasteful number, since it uses less digits than its factorization.

21405210042 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 26558.

The product of its (nonzero) digits is 640, while the sum is 21.

Adding to 21405210042 its reverse (24001250412), we get a palindrome (45406460454).

The spelling of 21405210042 in words is "twenty-one billion, four hundred five million, two hundred ten thousand, forty-two".