21390607 has 12 divisors (see below), whose sum is σ = 26347680. Its totient is φ = 17255616.

The previous prime is 21390601. The next prime is 21390613. The reversal of 21390607 is 70609312.

It is an interprime number because it is at equal distance from previous prime (21390601) and next prime (21390613).

It is not a de Polignac number, because 21390607 - 2¹¹ = 21388559 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21390601) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 12007 + ... + 13672.

It is an arithmetic number, because the mean of its divisors is an integer number (2195640).

Almost surely, 2^21390607 is an apocalyptic number.

21390607 is a deficient number, since it is larger than the sum of its proper divisors (4957073).

21390607 is a wasteful number, since it uses less digits than its factorization.

21390607 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 25710 (or 25703 counting only the distinct ones).

The product of its (nonzero) digits is 2268, while the sum is 28.

The square root of 21390607 is about 4624.9980540536. The cubic root of 21390607 is about 277.5924838508.

Adding to 21390607 its reverse (70609312), we get a palindrome (91999919).

It can be divided in two parts, 213 and 90607, that multiplied together give a palindrome (19299291).

The spelling of 21390607 in words is "twenty-one million, three hundred ninety thousand, six hundred seven".