21515041542001 has 12 divisors (see below), whose sum is σ = 25028700054948. Its totient is φ = 18440728317312.

The previous prime is 21515041541977. The next prime is 21515041542019. The reversal of 21515041542001 is 10024514051512.

It can be written as a sum of positive squares in 2 ways, for example, as 2723163340401 + 18791878201600 = 1650201^2 + 4334960^2 .

It is not a de Polignac number, because 21515041542001 - 2¹³ = 21515041533809 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21515041542901) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 7517956 + ... + 9977461.

It is an arithmetic number, because the mean of its divisors is an integer number (2085725004579).

Almost surely, 2^{21515041542001} is an apocalyptic number.

It is an amenable number.

21515041542001 is a deficient number, since it is larger than the sum of its proper divisors (3513658512947).

21515041542001 is a wasteful number, since it uses less digits than its factorization.

21515041542001 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 17520528 (or 17520521 counting only the distinct ones).

The product of its (nonzero) digits is 8000, while the sum is 31.

Adding to 21515041542001 its reverse (10024514051512), we get a palindrome (31539555593513).

The spelling of 21515041542001 in words is "twenty-one trillion, five hundred fifteen billion, forty-one million, five hundred forty-two thousand, one".