21506653401 has 32 divisors (see below), whose sum is σ = 30332559360. Its totient is φ = 13526720064.

The previous prime is 21506653387. The next prime is 21506653439. The reversal of 21506653401 is 10435660512.

It is not a de Polignac number, because 21506653401 - 2¹⁷ = 21506522329 is a prime.

It is a super-2 number, since 2×21506653401² (a number of 21 digits) contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (21506603401) 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, 8409615 + ... + 8412171.

It is an arithmetic number, because the mean of its divisors is an integer number (947892480).

Almost surely, 2^21506653401 is an apocalyptic number.

It is an amenable number.

21506653401 is a deficient number, since it is larger than the sum of its proper divisors (8825905959).

21506653401 is a wasteful number, since it uses less digits than its factorization.

21506653401 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4205.

The product of its (nonzero) digits is 21600, while the sum is 33.

The spelling of 21506653401 in words is "twenty-one billion, five hundred six million, six hundred fifty-three thousand, four hundred one".