21497351 has 2 divisors, whose sum is σ = 21497352. Its totient is φ = 21497350.

The previous prime is 21497339. The next prime is 21497369. The reversal of 21497351 is 15379412.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21497351 - 2¹⁰ = 21496327 is a prime.

It is a super-2 number, since 2×21497351² = 924272200034402, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21497321) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10748675 + 10748676.

It is an arithmetic number, because the mean of its divisors is an integer number (10748676).

Almost surely, 2^21497351 is an apocalyptic number.

21497351 is a deficient number, since it is larger than the sum of its proper divisors (1).

21497351 is an equidigital number, since it uses as much as digits as its factorization.

21497351 is an evil number, because the sum of its binary digits is even.

The product of its digits is 7560, while the sum is 32.

The square root of 21497351 is about 4636.5235899324. The cubic root of 21497351 is about 278.0534677967.

The spelling of 21497351 in words is "twenty-one million, four hundred ninety-seven thousand, three hundred fifty-one".