21156020115 has 16 divisors (see below), whose sum is σ = 35016861600. Its totient is φ = 10894134272.

The previous prime is 21156020113. The next prime is 21156020143. The reversal of 21156020115 is 51102065112.

It is a cyclic number.

It is not a de Polignac number, because 21156020115 - 2¹ = 21156020113 is a prime.

It is a super-2 number, since 2×21156020115² (a number of 21 digits) contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (21156020111) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 24316830 + ... + 24317699.

It is an arithmetic number, because the mean of its divisors is an integer number (2188553850).

Almost surely, 2^21156020115 is an apocalyptic number.

21156020115 is a deficient number, since it is larger than the sum of its proper divisors (13860841485).

21156020115 is a wasteful number, since it uses less digits than its factorization.

21156020115 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 48634566.

The product of its (nonzero) digits is 600, while the sum is 24.

Adding to 21156020115 its reverse (51102065112), we get a palindrome (72258085227).

The spelling of 21156020115 in words is "twenty-one billion, one hundred fifty-six million, twenty thousand, one hundred fifteen".