21406121601 has 16 divisors (see below), whose sum is σ = 30050529600. Its totient is φ = 13516573248.

The previous prime is 21406121593. The next prime is 21406121609. The reversal of 21406121601 is 10612160412.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (21406121593) and next prime (21406121609).

It is not a de Polignac number, because 21406121601 - 2³ = 21406121593 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21406121609) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 223815 + ... + 304803.

It is an arithmetic number, because the mean of its divisors is an integer number (1878158100).

Almost surely, 2^21406121601 is an apocalyptic number.

It is an amenable number.

21406121601 is a deficient number, since it is larger than the sum of its proper divisors (8644407999).

21406121601 is a wasteful number, since it uses less digits than its factorization.

21406121601 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 85648.

The product of its (nonzero) digits is 576, while the sum is 24.

The spelling of 21406121601 in words is "twenty-one billion, four hundred six million, one hundred twenty-one thousand, six hundred one".