21205354401 has 48 divisors (see below), whose sum is σ = 38617188480. Its totient is φ = 10891964160.

The previous prime is 21205354399. The next prime is 21205354403. The reversal of 21205354401 is 10445350212.

21205354401 is a `hidden beast` number, since 2 + 1 + 205 + 3 + 54 + 401 = 666.

It is an interprime number because it is at equal distance from previous prime (21205354399) and next prime (21205354403).

It is not a de Polignac number, because 21205354401 - 2¹ = 21205354399 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21205354403) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 110230 + ... + 233583.

It is an arithmetic number, because the mean of its divisors is an integer number (804524760).

Almost surely, 2^21205354401 is an apocalyptic number.

21205354401 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

It is an amenable number.

21205354401 is a deficient number, since it is larger than the sum of its proper divisors (17411834079).

21205354401 is a wasteful number, since it uses less digits than its factorization.

21205354401 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 343926 (or 343923 counting only the distinct ones).

The product of its (nonzero) digits is 4800, while the sum is 27.

The spelling of 21205354401 in words is "twenty-one billion, two hundred five million, three hundred fifty-four thousand, four hundred one".