21658338490 has 16 divisors (see below), whose sum is σ = 38989125000. Its totient is φ = 8662420800.

The previous prime is 21658338439. The next prime is 21658338517. The reversal of 21658338490 is 9483385612.

It can be written as a sum of positive squares in 4 ways, for example, as 21418615201 + 239723289 = 146351^2 + 15483^2 .

It is a super-2 number, since 2×21658338490² (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 7 ways as a sum of consecutive naturals, for example, 10365 + ... + 208384.

Almost surely, 2^21658338490 is an apocalyptic number.

21658338490 is a deficient number, since it is larger than the sum of its proper divisors (17330786510).

21658338490 is a wasteful number, since it uses less digits than its factorization.

21658338490 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 228657.

The product of its (nonzero) digits is 1244160, while the sum is 49.

The spelling of 21658338490 in words is "twenty-one billion, six hundred fifty-eight million, three hundred thirty-eight thousand, four hundred ninety".