21325915809 has 24 divisors (see below), whose sum is σ = 34064820192. Its totient is φ = 12747741120.

The previous prime is 21325915763. The next prime is 21325915843. The reversal of 21325915809 is 90851952312.

21325915809 is a `hidden beast` number, since 2 + 1 + 3 + 2 + 591 + 58 + 0 + 9 = 666.

It is not a de Polignac number, because 21325915809 - 2¹² = 21325911713 is a prime.

It is a super-2 number, since 2×21325915809² (a number of 21 digits) contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (21325915879) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 1468207 + ... + 1482660.

It is an arithmetic number, because the mean of its divisors is an integer number (1419367508).

Almost surely, 2^21325915809 is an apocalyptic number.

It is an amenable number.

21325915809 is a deficient number, since it is larger than the sum of its proper divisors (12738904383).

21325915809 is a wasteful number, since it uses less digits than its factorization.

21325915809 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2950957 (or 2950954 counting only the distinct ones).

The product of its (nonzero) digits is 194400, while the sum is 45.

The spelling of 21325915809 in words is "twenty-one billion, three hundred twenty-five million, nine hundred fifteen thousand, eight hundred nine".