21400037 has 2 divisors, whose sum is σ = 21400038. Its totient is φ = 21400036.

The previous prime is 21400031. The next prime is 21400063. The reversal of 21400037 is 73000412.

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., 17048641 + 4351396 = 4129^2 + 2086^2 .

It is a cyclic number.

It is not a de Polignac number, because 21400037 - 2²² = 17205733 is a prime.

It is a Chen prime.

It is a junction number, because it is equal to n+sod(n) for n = 21399988 and 21400024.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21400031) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10700018 + 10700019.

It is an arithmetic number, because the mean of its divisors is an integer number (10700019).

Almost surely, 2^21400037 is an apocalyptic number.

It is an amenable number.

21400037 is a deficient number, since it is larger than the sum of its proper divisors (1).

21400037 is an equidigital number, since it uses as much as digits as its factorization.

21400037 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 168, while the sum is 17.

The square root of 21400037 is about 4626.0174016102. The cubic root of 21400037 is about 277.6332698611.

Adding to 21400037 its reverse (73000412), we get a palindrome (94400449).

The spelling of 21400037 in words is "twenty-one million, four hundred thousand, thirty-seven".