21507007 has 2 divisors, whose sum is σ = 21507008. Its totient is φ = 21507006.

The previous prime is 21506999. The next prime is 21507071. The reversal of 21507007 is 70070512.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21507007 - 2³ = 21506999 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21507077) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10753503 + 10753504.

It is an arithmetic number, because the mean of its divisors is an integer number (10753504).

Almost surely, 2^21507007 is an apocalyptic number.

21507007 is a deficient number, since it is larger than the sum of its proper divisors (1).

21507007 is an equidigital number, since it uses as much as digits as its factorization.

21507007 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 490, while the sum is 22.

The square root of 21507007 is about 4637.5647704372. The cubic root of 21507007 is about 278.0950928074.

Adding to 21507007 its reverse (70070512), we get a palindrome (91577519).

The spelling of 21507007 in words is "twenty-one million, five hundred seven thousand, seven".