21520001242 has 8 divisors (see below), whose sum is σ = 34178825556. Its totient is φ = 10127059392.

The previous prime is 21520001233. The next prime is 21520001287. The reversal of 21520001242 is 24210002512.

It can be written as a sum of positive squares in 2 ways, for example, as 16017180481 + 5502820761 = 126559^2 + 74181^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a super-2 number, since 2×21520001242² (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 3 ways as a sum of consecutive naturals, for example, 316470573 + ... + 316470640.

Almost surely, 2^21520001242 is an apocalyptic number.

21520001242 is a deficient number, since it is larger than the sum of its proper divisors (12658824314).

21520001242 is a wasteful number, since it uses less digits than its factorization.

21520001242 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 632941232.

The product of its (nonzero) digits is 320, while the sum is 19.

Adding to 21520001242 its reverse (24210002512), we get a palindrome (45730003754).

The spelling of 21520001242 in words is "twenty-one billion, five hundred twenty million, one thousand, two hundred forty-two".