21151001 has 4 divisors (see below), whose sum is σ = 21338292. Its totient is φ = 20963712.

The previous prime is 21150991. The next prime is 21151027. The reversal of 21151001 is 10015112.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 9241600 + 11909401 = 3040^2 + 3451^2 .

It is a cyclic number.

It is not a de Polignac number, because 21151001 - 2⁶ = 21150937 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21151061) 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, 93476 + ... + 93701.

It is an arithmetic number, because the mean of its divisors is an integer number (5334573).

Almost surely, 2^21151001 is an apocalyptic number.

It is an amenable number.

21151001 is a deficient number, since it is larger than the sum of its proper divisors (187291).

21151001 is a wasteful number, since it uses less digits than its factorization.

21151001 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 187290.

The product of its (nonzero) digits is 10, while the sum is 11.

The square root of 21151001 is about 4599.0217438060. The cubic root of 21151001 is about 276.5521093120.

Adding to 21151001 its reverse (10015112), we get a palindrome (31166113).

The spelling of 21151001 in words is "twenty-one million, one hundred fifty-one thousand, one".