21516208545 has 16 divisors (see below), whose sum is σ = 37074082752. Its totient is φ = 10592594880.

The previous prime is 21516208541. The next prime is 21516208573. The reversal of 21516208545 is 54580261512.

It is not a de Polignac number, because 21516208545 - 2² = 21516208541 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (39).

It is not an unprimeable number, because it can be changed into a prime (21516208541) 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, 55169571 + ... + 55169960.

It is an arithmetic number, because the mean of its divisors is an integer number (2317130172).

Almost surely, 2^21516208545 is an apocalyptic number.

It is an amenable number.

21516208545 is a deficient number, since it is larger than the sum of its proper divisors (15557874207).

21516208545 is a wasteful number, since it uses less digits than its factorization.

21516208545 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 110339552.

The product of its (nonzero) digits is 96000, while the sum is 39.

The spelling of 21516208545 in words is "twenty-one billion, five hundred sixteen million, two hundred eight thousand, five hundred forty-five".