21397698 has 24 divisors (see below), whose sum is σ = 52985088. Its totient is φ = 6113592.

The previous prime is 21397697. The next prime is 21397699. The reversal of 21397698 is 89679312.

It is an interprime number because it is at equal distance from previous prime (21397697) and next prime (21397699).

It is a super-2 number, since 2×21397698² = 915722959398408, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (21397693) 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, 84786 + ... + 85037.

It is an arithmetic number, because the mean of its divisors is an integer number (2207712).

Almost surely, 2^21397698 is an apocalyptic number.

21397698 is an abundant number, since it is smaller than the sum of its proper divisors (31587390).

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

21397698 is a wasteful number, since it uses less digits than its factorization.

21397698 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 169838 (or 169835 counting only the distinct ones).

The product of its digits is 163296, while the sum is 45.

The square root of 21397698 is about 4625.7645854496. The cubic root of 21397698 is about 277.6231544911.

The spelling of 21397698 in words is "twenty-one million, three hundred ninety-seven thousand, six hundred ninety-eight".