21315154505 has 4 divisors (see below), whose sum is σ = 25578185412. Its totient is φ = 17052123600.

The previous prime is 21315154463. The next prime is 21315154547. The reversal of 21315154505 is 50545151312.

It is a semiprime because it is the product of two primes.

It is an interprime number because it is at equal distance from previous prime (21315154463) and next prime (21315154547).

It can be written as a sum of positive squares in 2 ways, for example, as 14473052416 + 6842102089 = 120304^2 + 82717^2 .

It is not a de Polignac number, because 21315154505 - 2¹⁴ = 21315138121 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2131515446 + ... + 2131515455.

It is an arithmetic number, because the mean of its divisors is an integer number (6394546353).

Almost surely, 2^21315154505 is an apocalyptic number.

It is an amenable number.

21315154505 is a deficient number, since it is larger than the sum of its proper divisors (4263030907).

21315154505 is an equidigital number, since it uses as much as digits as its factorization.

21315154505 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4263030906.

The product of its (nonzero) digits is 15000, while the sum is 32.

The spelling of 21315154505 in words is "twenty-one billion, three hundred fifteen million, one hundred fifty-four thousand, five hundred five".