21515204361 has 32 divisors (see below), whose sum is σ = 33218519040. Its totient is φ = 12132035136.

The previous prime is 21515204311. The next prime is 21515204419. The reversal of 21515204361 is 16340251512.

It is not a de Polignac number, because 21515204361 - 2²² = 21511010057 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21515204311) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 5849455 + ... + 5853131.

It is an arithmetic number, because the mean of its divisors is an integer number (1038078720).

Almost surely, 2^21515204361 is an apocalyptic number.

21515204361 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

It is an amenable number.

21515204361 is a deficient number, since it is larger than the sum of its proper divisors (11703314679).

21515204361 is a wasteful number, since it uses less digits than its factorization.

21515204361 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7293.

The product of its (nonzero) digits is 7200, while the sum is 30.

Adding to 21515204361 its reverse (16340251512), we get a palindrome (37855455873).

The spelling of 21515204361 in words is "twenty-one billion, five hundred fifteen million, two hundred four thousand, three hundred sixty-one".