21537001 has 2 divisors, whose sum is σ = 21537002. Its totient is φ = 21537000.

The previous prime is 21536989. The next prime is 21537029. The reversal of 21537001 is 10073512.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 19053225 + 2483776 = 4365^2 + 1576^2 .

It is a cyclic number.

It is not a de Polignac number, because 21537001 - 2⁷ = 21536873 is a prime.

It is a Chen prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21537001.

It is not a weakly prime, because it can be changed into another prime (21537091) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10768500 + 10768501.

It is an arithmetic number, because the mean of its divisors is an integer number (10768501).

Almost surely, 2^21537001 is an apocalyptic number.

It is an amenable number.

21537001 is a deficient number, since it is larger than the sum of its proper divisors (1).

21537001 is an equidigital number, since it uses as much as digits as its factorization.

21537001 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 210, while the sum is 19.

The square root of 21537001 is about 4640.7974530246. The cubic root of 21537001 is about 278.2243113087.

The spelling of 21537001 in words is "twenty-one million, five hundred thirty-seven thousand, one".