20961398 has 4 divisors (see below), whose sum is σ = 31442100. Its totient is φ = 10480698.

The previous prime is 20961397. The next prime is 20961433. The reversal of 20961398 is 89316902.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 89316902 = 2 ⋅44658451.

It is a super-2 number, since 2×20961398² = 878760412228808, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20961397) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5240348 + ... + 5240351.

It is an arithmetic number, because the mean of its divisors is an integer number (7860525).

Almost surely, 2^20961398 is an apocalyptic number.

20961398 is a deficient number, since it is larger than the sum of its proper divisors (10480702).

20961398 is a wasteful number, since it uses less digits than its factorization.

20961398 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10480701.

The product of its (nonzero) digits is 23328, while the sum is 38.

The square root of 20961398 is about 4578.3619341419. The cubic root of 20961398 is about 275.7232663468.

The spelling of 20961398 in words is "twenty million, nine hundred sixty-one thousand, three hundred ninety-eight".