21662001 has 12 divisors (see below), whose sum is σ = 31880628. Its totient is φ = 14168544.

The previous prime is 21661999. The next prime is 21662041. The reversal of 21662001 is 10026612.

It is a happy number.

21662001 is a `hidden beast` number, since 2 + 1 + 662 + 0 + 0 + 1 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 6051600 + 15610401 = 2460^2 + 3951^2 .

It is not a de Polignac number, because 21662001 - 2¹ = 21661999 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21662041) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 22230 + ... + 23183.

It is an arithmetic number, because the mean of its divisors is an integer number (2656719).

Almost surely, 2^21662001 is an apocalyptic number.

It is an amenable number.

21662001 is a deficient number, since it is larger than the sum of its proper divisors (10218627).

21662001 is a wasteful number, since it uses less digits than its factorization.

21662001 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 45472 (or 45469 counting only the distinct ones).

The product of its (nonzero) digits is 144, while the sum is 18.

The square root of 21662001 is about 4654.2454812784. The cubic root of 21662001 is about 278.7615413455.

Adding to 21662001 its reverse (10026612), we get a palindrome (31688613).

The spelling of 21662001 in words is "twenty-one million, six hundred sixty-two thousand, one".