21505332402 has 24 divisors (see below), whose sum is σ = 46961780736. Its totient is φ = 7111998936.

The previous prime is 21505332379. The next prime is 21505332439. The reversal of 21505332402 is 20423350512.

It is a happy number.

It is a super-2 number, since 2×21505332402² (a number of 21 digits) contains 22 as substring.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 4701418 + ... + 4705989.

It is an arithmetic number, because the mean of its divisors is an integer number (1956740864).

Almost surely, 2^21505332402 is an apocalyptic number.

21505332402 is an abundant number, since it is smaller than the sum of its proper divisors (25456448334).

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

21505332402 is a wasteful number, since it uses less digits than its factorization.

21505332402 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9407542 (or 9407539 counting only the distinct ones).

The product of its (nonzero) digits is 7200, while the sum is 27.

Adding to 21505332402 its reverse (20423350512), we get a palindrome (41928682914).

The spelling of 21505332402 in words is "twenty-one billion, five hundred five million, three hundred thirty-two thousand, four hundred two".