21397026 has 64 divisors (see below), whose sum is σ = 51436800. Its totient is φ = 5927040.

The previous prime is 21397009. The next prime is 21397043. The reversal of 21397026 is 62079312.

It is an interprime number because it is at equal distance from previous prime (21397009) and next prime (21397043).

It is a junction number, because it is equal to n+sod(n) for n = 21396984 and 21397002.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 76006 + ... + 76286.

It is an arithmetic number, because the mean of its divisors is an integer number (803700).

Almost surely, 2^21397026 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21397026, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (25718400).

21397026 is an abundant number, since it is smaller than the sum of its proper divisors (30039774).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21397026 is a wasteful number, since it uses less digits than its factorization.

21397026 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 344 (or 330 counting only the distinct ones).

The product of its (nonzero) digits is 4536, while the sum is 30.

The square root of 21397026 is about 4625.6919482387. The cubic root of 21397026 is about 277.6202481860.

The spelling of 21397026 in words is "twenty-one million, three hundred ninety-seven thousand, twenty-six".