21400597 has 2 divisors, whose sum is σ = 21400598. Its totient is φ = 21400596.

The previous prime is 21400591. The next prime is 21400667. The reversal of 21400597 is 79500412.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 18714276 + 2686321 = 4326^2 + 1639^2 .

It is a cyclic number.

It is not a de Polignac number, because 21400597 - 2¹⁹ = 20876309 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21400591) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10700298 + 10700299.

It is an arithmetic number, because the mean of its divisors is an integer number (10700299).

Almost surely, 2^21400597 is an apocalyptic number.

It is an amenable number.

21400597 is a deficient number, since it is larger than the sum of its proper divisors (1).

21400597 is an equidigital number, since it uses as much as digits as its factorization.

21400597 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 2520, while the sum is 28.

The square root of 21400597 is about 4626.0779284400. The cubic root of 21400597 is about 277.6356915590.

The spelling of 21400597 in words is "twenty-one million, four hundred thousand, five hundred ninety-seven".