21640601 has 4 divisors (see below), whose sum is σ = 22779600. Its totient is φ = 20501604.

The previous prime is 21640561. The next prime is 21640607. The reversal of 21640601 is 10604612.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 21640601 - 2⁶ = 21640537 is a prime.

It is a super-2 number, since 2×21640601² = 936631223282402, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21640607) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 569471 + ... + 569508.

It is an arithmetic number, because the mean of its divisors is an integer number (5694900).

Almost surely, 2^21640601 is an apocalyptic number.

It is an amenable number.

21640601 is a deficient number, since it is larger than the sum of its proper divisors (1138999).

21640601 is a wasteful number, since it uses less digits than its factorization.

21640601 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1138998.

The product of its (nonzero) digits is 288, while the sum is 20.

The square root of 21640601 is about 4651.9459369172. The cubic root of 21640601 is about 278.6697144561.

The spelling of 21640601 in words is "twenty-one million, six hundred forty thousand, six hundred one".