21715001 has 32 divisors (see below), whose sum is σ = 29299968. Its totient is φ = 15575040.

The previous prime is 21714989. The next prime is 21715003. The reversal of 21715001 is 10051712.

It is a cyclic number.

It is not a de Polignac number, because 21715001 - 2⁶ = 21714937 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (17).

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21715003) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 69221 + ... + 69533.

It is an arithmetic number, because the mean of its divisors is an integer number (915624).

Almost surely, 2^21715001 is an apocalyptic number.

It is an amenable number.

21715001 is a deficient number, since it is larger than the sum of its proper divisors (7584967).

21715001 is a wasteful number, since it uses less digits than its factorization.

21715001 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 401.

The product of its (nonzero) digits is 70, while the sum is 17.

The square root of 21715001 is about 4659.9357291705. The cubic root of 21715001 is about 278.9887030108.

Adding to 21715001 its reverse (10051712), we get a palindrome (31766713).

The spelling of 21715001 in words is "twenty-one million, seven hundred fifteen thousand, one".