21515222553 has 8 divisors (see below), whose sum is σ = 31294869216. Its totient is φ = 13039528800.

The previous prime is 21515222543. The next prime is 21515222581. The reversal of 21515222553 is 35522251512.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 21515222553 - 2⁸ = 21515222297 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (33), and also a Moran number because the ratio is a prime number: 651976441 = 21515222553 / (2 + 1 + 5 + 1 + 5 + 2 + 2 + 2 + 5 + 5 + 3).

It is not an unprimeable number, because it can be changed into a prime (21515222503) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 325988188 + ... + 325988253.

It is an arithmetic number, because the mean of its divisors is an integer number (3911858652).

Almost surely, 2^21515222553 is an apocalyptic number.

It is an amenable number.

21515222553 is a deficient number, since it is larger than the sum of its proper divisors (9779646663).

21515222553 is a wasteful number, since it uses less digits than its factorization.

21515222553 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 651976455.

The product of its digits is 30000, while the sum is 33.

It can be divided in two parts, 215152 and 22553, that added together give a triangular number (237705 = T₆₈₉).

The spelling of 21515222553 in words is "twenty-one billion, five hundred fifteen million, two hundred twenty-two thousand, five hundred fifty-three".