21812597493 has 64 divisors (see below), whose sum is σ = 32490823680. Its totient is φ = 12964492800.

The previous prime is 21812597489. The next prime is 21812597497. The reversal of 21812597493 is 39479521812.

It is an interprime number because it is at equal distance from previous prime (21812597489) and next prime (21812597497).

It is not a de Polignac number, because 21812597493 - 2² = 21812597489 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21812597497) by changing a digit.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 7797171 + ... + 7799967.

It is an arithmetic number, because the mean of its divisors is an integer number (507669120).

Almost surely, 2^21812597493 is an apocalyptic number.

It is an amenable number.

21812597493 is a deficient number, since it is larger than the sum of its proper divisors (10678226187).

21812597493 is a wasteful number, since it uses less digits than its factorization.

21812597493 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2978.

The product of its digits is 1088640, while the sum is 51.

The spelling of 21812597493 in words is "twenty-one billion, eight hundred twelve million, five hundred ninety-seven thousand, four hundred ninety-three".