21510021042 has 32 divisors (see below), whose sum is σ = 48040272000. Its totient is φ = 7133973264.

The previous prime is 21510020989. The next prime is 21510021047. The reversal of 21510021042 is 24012001512.

It is a Harshad number since it is a multiple of its sum of digits (18).

It is not an unprimeable number, because it can be changed into a prime (21510021047) 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, 990093 + ... + 1011584.

It is an arithmetic number, because the mean of its divisors is an integer number (1501258500).

Almost surely, 2^21510021042 is an apocalyptic number.

21510021042 is an abundant number, since it is smaller than the sum of its proper divisors (26530250958).

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

21510021042 is a wasteful number, since it uses less digits than its factorization.

21510021042 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2001887 (or 2001881 counting only the distinct ones).

The product of its (nonzero) digits is 160, while the sum is 18.

Adding to 21510021042 its reverse (24012001512), we get a palindrome (45522022554).

The spelling of 21510021042 in words is "twenty-one billion, five hundred ten million, twenty-one thousand, forty-two".