21725001 has 24 divisors (see below), whose sum is σ = 32148480. Its totient is φ = 14134176.

The previous prime is 21724991. The next prime is 21725003. The reversal of 21725001 is 10052712.

It is not a de Polignac number, because 21725001 - 2¹³ = 21716809 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21725003) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 94755 + ... + 94983.

It is an arithmetic number, because the mean of its divisors is an integer number (1339520).

Almost surely, 2^21725001 is an apocalyptic number.

It is an amenable number.

21725001 is a deficient number, since it is larger than the sum of its proper divisors (10423479).

21725001 is a wasteful number, since it uses less digits than its factorization.

21725001 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 445 (or 442 counting only the distinct ones).

The product of its (nonzero) digits is 140, while the sum is 18.

The square root of 21725001 is about 4661.0085818415. The cubic root of 21725001 is about 279.0315222410.

Adding to 21725001 its reverse (10052712), we get a palindrome (31777713).

The spelling of 21725001 in words is "twenty-one million, seven hundred twenty-five thousand, one".