21953001 has 16 divisors (see below), whose sum is σ = 35420544. Its totient is φ = 11806464.

The previous prime is 21952993. The next prime is 21953011. The reversal of 21953001 is 10035912.

It is not a de Polignac number, because 21953001 - 2³ = 21952993 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (21).

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (21953011) 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, 30390 + ... + 31103.

It is an arithmetic number, because the mean of its divisors is an integer number (2213784).

Almost surely, 2^21953001 is an apocalyptic number.

21953001 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

It is an amenable number.

21953001 is a deficient number, since it is larger than the sum of its proper divisors (13467543).

21953001 is a wasteful number, since it uses less digits than its factorization.

21953001 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 61520.

The product of its (nonzero) digits is 270, while the sum is 21.

The square root of 21953001 is about 4685.4029709300. The cubic root of 21953001 is about 280.0042558877.

Adding to 21953001 its reverse (10035912), we get a palindrome (31988913).

The spelling of 21953001 in words is "twenty-one million, nine hundred fifty-three thousand, one".