21400061 has 4 divisors (see below), whose sum is σ = 22526400. Its totient is φ = 20273724.

The previous prime is 21400037. The next prime is 21400063. The reversal of 21400061 is 16000412.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 21400061 - 2¹⁸ = 21137917 is a prime.

It is a super-2 number, since 2×21400061² = 915925221607442, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21400063) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 563141 + ... + 563178.

It is an arithmetic number, because the mean of its divisors is an integer number (5631600).

Almost surely, 2^21400061 is an apocalyptic number.

It is an amenable number.

21400061 is a deficient number, since it is larger than the sum of its proper divisors (1126339).

21400061 is a wasteful number, since it uses less digits than its factorization.

21400061 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1126338.

The product of its (nonzero) digits is 48, while the sum is 14.

The square root of 21400061 is about 4626.0199956334. The cubic root of 21400061 is about 277.6333736490.

Adding to 21400061 its reverse (16000412), we get a palindrome (37400473).

The spelling of 21400061 in words is "twenty-one million, four hundred thousand, sixty-one".