21515401011 has 16 divisors (see below), whose sum is σ = 30896812800. Its totient is φ = 13239002400.

The previous prime is 21515401003. The next prime is 21515401021. The reversal of 21515401011 is 11010451512.

It is not a de Polignac number, because 21515401011 - 2³ = 21515401003 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21515401001) 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, 564640 + ... + 601538.

It is an arithmetic number, because the mean of its divisors is an integer number (1931050800).

Almost surely, 2^21515401011 is an apocalyptic number.

21515401011 is a deficient number, since it is larger than the sum of its proper divisors (9381411789).

21515401011 is a wasteful number, since it uses less digits than its factorization.

21515401011 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 51866.

The product of its (nonzero) digits is 200, while the sum is 21.

Adding to 21515401011 its reverse (11010451512), we get a palindrome (32525852523).

The spelling of 21515401011 in words is "twenty-one billion, five hundred fifteen million, four hundred one thousand, eleven".