21651056401 has 16 divisors (see below), whose sum is σ = 24698510928. Its totient is φ = 18802022400.

The previous prime is 21651056389. The next prime is 21651056423. The reversal of 21651056401 is 10465015612.

It can be written as a sum of positive squares in 8 ways, for example, as 958521600 + 20692534801 = 30960^2 + 143849^2 .

It is a cyclic number.

It is not a de Polignac number, because 21651056401 - 2¹¹ = 21651054353 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21651056461) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 537711 + ... + 576571.

It is an arithmetic number, because the mean of its divisors is an integer number (1543656933).

Almost surely, 2^21651056401 is an apocalyptic number.

It is an amenable number.

21651056401 is a deficient number, since it is larger than the sum of its proper divisors (3047454527).

21651056401 is a wasteful number, since it uses less digits than its factorization.

21651056401 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 41412.

The product of its (nonzero) digits is 7200, while the sum is 31.

The spelling of 21651056401 in words is "twenty-one billion, six hundred fifty-one million, fifty-six thousand, four hundred one".