21515243215401 has 24 divisors (see below), whose sum is σ = 33469533377280. Its totient is φ = 13239604819296.

The previous prime is 21515243215391. The next prime is 21515243215429. The reversal of 21515243215401 is 10451234251512.

21515243215401 is a `hidden beast` number, since 2 + 1 + 5 + 1 + 5 + 243 + 2 + 1 + 5 + 401 = 666.

It is not a de Polignac number, because 21515243215401 - 2⁷ = 21515243215273 is a prime.

It is a super-2 number, since 2×21515243215401² (a number of 27 digits) contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (21515243215201) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 919161 + ... + 6623846.

It is an arithmetic number, because the mean of its divisors is an integer number (1394563890720).

Almost surely, 2^{21515243215401} is an apocalyptic number.

It is an amenable number.

21515243215401 is a deficient number, since it is larger than the sum of its proper divisors (11954290161879).

21515243215401 is a wasteful number, since it uses less digits than its factorization.

21515243215401 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7567405 (or 7567402 counting only the distinct ones).

The product of its (nonzero) digits is 48000, while the sum is 36.

Adding to 21515243215401 its reverse (10451234251512), we get a palindrome (31966477466913).

The spelling of 21515243215401 in words is "twenty-one trillion, five hundred fifteen billion, two hundred forty-three million, two hundred fifteen thousand, four hundred one".