21344502591 has 32 divisors (see below), whose sum is σ = 32364334080. Its totient is φ = 13896701568.

The previous prime is 21344502577. The next prime is 21344502607. The reversal of 21344502591 is 19520544312.

21344502591 is a `hidden beast` number, since 2 + 13 + 4 + 4 + 50 + 2 + 591 = 666.

It is not a de Polignac number, because 21344502591 - 2⁹ = 21344502079 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21344502691) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 574615 + ... + 610631.

It is an arithmetic number, because the mean of its divisors is an integer number (1011385440).

Almost surely, 2^21344502591 is an apocalyptic number.

21344502591 is a deficient number, since it is larger than the sum of its proper divisors (11019831489).

21344502591 is a wasteful number, since it uses less digits than its factorization.

21344502591 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 36540 (or 36534 counting only the distinct ones).

The product of its (nonzero) digits is 43200, while the sum is 36.

The spelling of 21344502591 in words is "twenty-one billion, three hundred forty-four million, five hundred two thousand, five hundred ninety-one".