21247209007 has 4 divisors (see below), whose sum is σ = 21442137640. Its totient is φ = 21052280376.

The previous prime is 21247208999. The next prime is 21247209023. The reversal of 21247209007 is 70090274212.

It is a happy number.

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

It is a cyclic number.

It is not a de Polignac number, because 21247209007 - 2³ = 21247208999 is a prime.

It is a super-3 number, since 3×21247209007³ (a number of 32 digits) contains 333 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21247209047) 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, 97464153 + ... + 97464370.

It is an arithmetic number, because the mean of its divisors is an integer number (5360534410).

Almost surely, 2^21247209007 is an apocalyptic number.

21247209007 is a deficient number, since it is larger than the sum of its proper divisors (194928633).

21247209007 is a wasteful number, since it uses less digits than its factorization.

21247209007 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 194928632.

The product of its (nonzero) digits is 14112, while the sum is 34.

The spelling of 21247209007 in words is "twenty-one billion, two hundred forty-seven million, two hundred nine thousand, seven".